As given in your question, when も "mo" is used in affirmative sense, it means "too" or "also".
When it is used in negative sense, it has a general meaning of "not ... at all". For instance,
何でも ない。(nan demo nai.) = There is nothing at all.
私は どこにも 行きません。(watashi-wa doko-nimo ikimasen.) = I do not go to anywhere at all.
Sometimes, when it is used in questions (interrogations), it has a meaning of "even" or "even if". For instance,
英語で 話しても いいですか。(eigo-de hanashitemo iidesuka?) = Is it alright (even) if we speak in English? [This was what I usually said years ago when I visited Japan with very limited conversational ability using solely Japanese. :)]
N.B. I encourage any Japanese speaking members to provide further examples or usages, should I have missed any information.
Good day. / 良い一日を。