いつでも (itsudemo) means “anytime” | MotiTan Japanese Dictionary

More examples

いつでも質問してください。i tsu de mo shitsu mon shi te ku da sa i

Please ask questions anytime.

It indicates that no particular time is required, so an action may take place whenever the circumstances allow.

随時zuiji: At any time when the circumstances allow, often in formal notices.
いつもitsumo: On every occasion or as a regular habit.

特定の時に限らず、都合のよい時ならどの時でも。toku tei no toki ni kagi ra zu tsu gō no yo i toki na ra do no toki de mo

The adverb いつでも (itsudemo) is formed from いつ (itsu, "when") and でも (demo, "even" or "also"), giving the sense of any time.

The phrase いつでもどうぞ (itsudemo dōzo) makes an invitation sound open-ended, while always refers to something that happens on every occasion.