All lenses should have a filter. The main reason is to protect the actual lens glass & its special coating. It’s easier to clean & replace a filter than a lens!
The most common filters are ‘Skylight’ & ‘UV’ filters. We photographers put them on, and leave them on. We will swap them out for others, when needed.
UV & Skylight filters reduce the amount of ‘blue’ that can come thru on outdoor shoots. Most won’t notice the slight reduction of the blue cast in outdoor photography. But then again, with Photoshop & such, the blue can be altered to suit the shot.
Again, mainly to protect the lens glass itself. They come in a wide range of sizes. I’ve seen some ‘point & shoot’ cameras with threading to allow the addition of a lens filter.
Circular Polarizer filter: This is probably the next most common filter in a photographer’s kit bag. Add it can help ‘punch up’ colors & will reduces glare & reflections. Reflections off water, or off a window front.. You can get some pretty dramatic sky & clouds with one. The outer ring rotates, so you can align the polarizer to match the light waves.
There are a myriad of other filter types, some artistic, some limit certain color wavelengths.. But anybody starting out should have at minimum a UV or skylight on each lens..