Vowels in Spanish have a lot of meanings. They differentiate the gender of nouns and adjectives: the ending –o stands for the masculine gender, and the ending –a, the feminine gender:
Alberto (a boy) – Alberta (a girl)
amigo (msculine friend) – amiga (femenine friend)
hermano (a brother) – hermana (a sister)
blanco (something white in masculine) – blanca (something white in femenine)
Unclear pronunciation of an ending can change a man into a woman.
The ending –o in the verbs in the present tense indicates the first person (“I”), and the endings –a, –e, the third person (“he or she”):
canto (I sing) – canta (She or he sings)
vivo (I live) – vive (She or he lives)
Therefore, before reading texts and dialogues, underline all the vowels and pay a lot of attention to the ending. It should sound perfectly clear.