Yes, you can definitely substitute - you'll get a slightly different texture in some things, especially pie pastry (vegetable shortening tends to be more fluffy/flaky, butter a little more tender and easier to brown around the edges), and of course butter has flavor. I prefer butter for everything unless I have a reason to go vegan, but a half-and-half mixture works fine and is a good compromise in most things.

Solid vegetable fat is very commonly used in baking in the US - you'll find a lot of info that's more tailored for particular kinds of recipes if you google "shortening" or "Crisco" (which is the most common US brand name, commonly used as a generic term). Note that most are hydrogenated oils (and so prone to trans-fat issues) rather than naturally solid at room temp - the exceptions are mostly tropical oils, which may not be flavor-neutral and may have environmental downsides.