The ь is a soft sign. Meaning that any letter coming before it is pronounced softly. ъ is a hard sign. Meaning that any letter coming before it is pronounced in a hard manner. If I am wrong in any way then may there be a native or more experienced learner come and correct me.
What Blake said, where Soft means palatalized, that is pronounced as if there were a following Y sound, and Hard means not palatalized, even if the following vowel begins with a Y sound.
That said, I don't understand what it's doing in this word, since the following vowel does begin with a Y sound, so as I understand it, that should make the consonant Soft already.
There are two ways to spell it. https://dictionary.cambridge.org/dictionary/english-russian/girl. My answer should be accepted.
@remisorus - Yes.
Пить is the imperfective form of the verb "to drink". You would use to show ongoing action in the past, present or future tenses (I was drinking, I am drinking), or to show habitual action (I normally drink coffee in the morning and tea at night).
Выпить is perfective aspect - it shows a one time action that was completed in the past or that will be completed in the future. It means more like "drink up" (выпить чашку чая = completely drink a cup of tea), and it's also commonly used with alcohol. The imperfective form is выпивать.