Learn Spanish (Latin America): A mi perro le gustan los juguetes pequeños.

Because the things being liked—the toys (los juguetes)—are plural. The verb gustar actually works like 'to be pleasing to.' Since multiple toys are pleasing to the dog, we use the plural form gustan.

Why does the sentence start with A?

Because gustar translates more literally accurately to 'to be pleasing to,' we use A to introduce who is experiencing the feeling. A mi perro literally means 'To my dog.'

Why do we need the word le if we already said A mi perro?

In Spanish, verbs like gustar require a pronoun to show who is being pleased—in this case, le ('to him/it'). Even though we already specified 'to my dog' (A mi perro), Spanish grammar strictly requires you to include le anyway. It feels repetitive to English speakers, but it is mandatory in Spanish!

Why is it los juguetes? The English translation just says 'small toys,' not 'the small toys.'

When you use gustar to say someone likes certain things, Spanish requires you to put the definite article (el, la, los, or las) before the noun, even if we leave out 'the' in English.