疑問詞+でも
Any… (anything/anyone/anywhere/anytime)machine translation
FormationQuestion word (何・誰・どこ・いつ…) + でも
Question word + でも creates the meaning "any…": 何でも (anything), 誰でも (anyone), どこでも (anywhere), いつでも (anytime), どれでも (any one of them is fine).
This pattern always goes with an AFFIRMATIVE sentence: 何でも食べられます (I can eat anything). Be careful not to confuse it with question word + も + negative, which you learned at N5: 何も食べません (I don't eat anything), 誰もいません (there's no one). The short version: affirmative → でも, negative → も.
This kind of でも shows up a lot in invitations and permissions: いつでも聞いてください (feel free to ask anytime), どれでもいいですよ (any of them is fine).
Examples
私は何でも食べられます。
I can eat anything.
この公園は誰でも入ることができます。
Anyone can enter this park.
分からないことがあったら、いつでも聞いてください。
If there's anything you don't understand, feel free to ask me anytime.