"When will you come?"
Translation:तुम कब आओगे ?
आऊंगी is the feminine first-person form to be used with मैं when you are female.
आओगी is a feminine second-person form to be used with तुम when the person you're talking to is female.
The other two second-person forms to be used with आप and तू respectively are आएंगी and आएगी which are incidentally also the feminine plural and singular third-person forms
I have listed the future-tense forms for three verbs (आना, पीना, करना).
First-person singular (मैं) : आऊँगा/पिऊँगा/करूँगा (m) and आऊँगी/पिऊँगी/करुँगी (f)
Third-person singular and तू : आएगा/पिएगा/करेगा (m) and आएगी/पिएगी/करेगी (f)
तुम: आओगे/पिओगे/करोगे (m) and आओगी/पिओगी/करोगी (f)
Third-person plural, first-person plural (हम) and आप : आएँगे/पिएँगे/करेंगे (m) and आएँगी/पिएँगी/करेंगी (f)
You will notice that future tense forms mostly involve adding certain suffixes to the root form of the verb (what you get when you remove the ना from the verb infinitive). For masc. first person singular, we add ऊँगा, for masc. third-person singular we add एगा etc. The feminine suffix is just the masculine suffix with ी instead of ा or े at the end. Just note that for certain verbs, the ending of the root may be slightly changed before you add the suffix. For example, for पीना, you add the suffix to पि instead of पी. Similarly, for देना, you add the suffix to द instead of दे for some forms making the masculine first person singular form दूँगा and so on.
Note: In all the forms which have ए which is not attached to a consonant, you also have alternate spellings replacing it with ये. Eg: खायेगा/खाएगा, खाएँगे/खायेंगे etc. Similarly, there exist alternate spellings with ओ replaced with यो or वो.