Learn Spanish (Spain): A mi hermano no le gustan los tigres blancos.

In Spanish, the verb gustar works differently than 'to like' in English. It literally means 'to be pleasing to'. The sentence is really saying 'White tigers are not pleasing to my brother'. Since the tigers (plural) are doing the pleasing, you must use the plural verb gustan.

Why do we need both A mi hermano and le?

The pronoun le is required here, but it can mean 'to him', 'to her', or 'to you (formal)'. We add A mi hermano at the beginning to clarify exactly who we are talking about.

In English we just say 'white tigers'. Why does Spanish add los?

Whenever you talk about things you like or dislike in general, Spanish requires you to use the definite article (el, la, los, or las) before the noun.

Where does the word no go when making this sentence negative?

The word no must go immediately before the pronoun (le). You can never separate the pronoun from the verb (gustan).