[sentence]。でも、[sentence]。 [noun] + でも + [suggestion] [question word] + でも [noun] + でも ("even")
This is the everyday word for "but", in speech and in casual writing. Formal writing uses しかし.
でも cannot glue two halves into one sentence: ×この本は高いですでも、買いたいです. Inside a sentence, "but" is けど or が at the end of the first half.
These go beyond "but". After a noun or a question word, でも is a different word.
After a noun, でも offers the noun as one example, which makes an invitation or a suggestion sound relaxed. The particle を drops out.
A question word plus でも means every possible answer is fine.
With an extreme example in front of it, でも means "even": if it holds for this case, it holds for the others too.
After a noun that names a situation, it is "even if it is".