Everybody will be suggesting different cameras, different types of cameras, this vs. that, etc. Being older, I learned about photography with film cameras. With digital cameras you do not need to know nearly as much about how cameras function because they all have various automatic modes for almost any situation. But, I personally feel that if you understand the fundamentals of lenses and cameras, you can be a better, and more creative photographer, regardless of the camera. And my advice is to take a course that teaches the fundamentals, and even consider buying a used manual, film SLR, to understand the fundamentals. Many can be found at very cheap prices in some pawn shops.
My first serious camera was an Olympus OM-1, SLR. Manual focus, manual F-stop, or aperture setting for the amount of light admitted, manual shutter speed, for the amount of time the film was exposed to the light (image), and an exposure meter to show how those settings would affect the exposure. Another variable that had to be considered was the speed rating of the film used, but that is one thing that digital photography does not require.
SLR, or single lens reflex, meant that looking in the viewfinder, you saw through the lens the image the film captured when exposed. This was done via mirrors, with the last mirror blocking the image from the film until exposure. When the photo button was depressed, that mirror raised, allowing the film to be exposed to that image, and then dropped back down to stop the exposure. The time of exposure was the shutter speed, such as 1/4,000 of a second, to 30 seconds. Digital cameras have these ratings.
There was a button to show the depth of field (whether or not objects closer than, or farther away from the subject were also in focus). There was a ring located on the lens mount, to change the shutter speed. Faster speeds were used to freeze moving objects, but less time for light to affect exposure. So, opening the aperture allows more light in. Most digital SLRs also have this for manual operation.
You had to manually focus the lens via the lens ring. You had to adjust the shutter speed (the length of time the shutter is open to admit light). And you had to set the aperture, or F-stop, i.e F1.8 to F22 (how wide the lens opening is, to affect how much light is admitted). F1.8 is the widest the aperture is set, allowing the most light, and F22 the narrowest, allowing the least amount of light. At F1.8, the focus is sharpest on the subject, with objects in front of, or closer than, and those farther behind, being less focused, or blurry. At F22, not only is the subject in focus, but also objects closer and farther away. But at F22, because less light is admitted, the slower the shutter speed needed to be for proper exposure. While auto focus is standard, many allow for manual focus.
Looking in the viewfinder, the meter would show if the settings properly exposed the film for the optimal photo. If the meter showed minus, or underexposed, you could either slow down the shutter speed to increase the time that the film has to capture enough light, or change the F-stop, or aperture setting, to allow more light in at the desired shutter speed. Today's SLRs have viewfinder meters, that do that, and provide much more info.
Camera lenses, even today, are constructed to operate the same as the eye. Bright light causes the corneas to become smaller, lessening the amount of light admitted, or necessary to see an image. And low light causes the corneas to become larger, allowing more light in, to see an image. That is why in very bright light, you might squint your eyes to limit the light. Cats have better night vision in part because their corneas can open larger in proportion to size of their eyes.
The camera lens operates the same. The aperture, or lens opening, is widened to allow more light, as in cases of low light situations, and narrowed in bright light, because less light is needed for exposure. Lenses are rated for aperture range, such as F1.8 to F22, F1.8 being the largest opening, and F22 being the smallest opening. These openings are referred to as F-stops. A lens rated as F1.2 at the widest setting, is a faster lens than F1.8., because it can let in more light, and therefore requires less time to be exposed. To achieve this, the lens is usually more complex, requiring more, and/or larger lens elements to achieve higher light admittance, and these usually cost much more to produce, and are usually heavier and/or bulkier.
I know this was a lot of rambling, but some may benefit from the knowledge.