Tú the second person, singular pronoun you.
Féin has a number of slightly different meanings, depending on context. When used after pronouns, it means -self, -selves.
Thus, tú féin: yourself.
In spoken Irish, féin is often pronounced héin, especially when following a vowel sound (the héin form is particularly strong in Donegal Irish) and the non-standard spelling fhéin is often seen used to reflect this.
Strictly speaking, this is incorrect even outside the constrictions of the official standard spelling as aspirated initial f sounds (fh-) are totally unvoiced. Compare and contrast these examples:
In Munster féin / héin are often, though not always, pronounced féinig / héinig.