To speak about our likes and dislikes, we need the verb GUSTAR.
GUSTAR = to please
To talk about my likes and dislikes, I use the following forms of the verb GUSTAR in present tense:
Me gusta = it pleases me
Me gustan = they please me
No me gusta = it does not please me
No me gustan = they do not please me
In other words, the meaning of "me gusta" and "me gustan" is "I like". However, in Spanish we express our likes and dislikes in a reversed way: instead of saying "I like chocolate", we say "to me chocolate is pleasing" or "chocolate pleases me". Thus, the subject of the verb "pleases" is not "I" but "chocolate".
That's why in Spanish, I say:
I use "me gusta" (3rd person of singular) because the subject (el chocolate) is singular.
Me gustan los* chocolates.
I use "me gustan" (3rd person of plural) because the subject (los chocolates) is plural.
*Note: the definite article (el, la, los, las) is required after the verb GUSTAR.