Learn Spanish (Spain): ¿Puedes ayudar?

Puedes comes from the verb poder (to be able to / can). It is a stem-changing verb. This means that when we conjugate it, the o in the root of the word changes to ue for most forms, including tú puedes (you can).

Where is the word for "you" in this sentence?

In Spanish, the ending of the verb usually tells us who is doing the action. The -es ending in puedes already means "you" (informal singular). Because of this, you don't need to include the word tú, although it wouldn't be wrong if you did.

Why doesn't ayudar change to match "you" as well?

When you have two verbs acting together like this, only the first verb gets conjugated (changed to match the person). The second verb stays in its dictionary form, called the infinitive. So, you use the conjugated puedes followed by the unchanged ayudar.

Does puedes translate to "can you" or "are you able to"?

It translates to both! English has two different ways to express this idea, but Spanish just uses the verb poder.