Learn Spanish (Latin America): Donarías mucho dinero al hospital. - You would donate a lot of money to the hospital.

To form the conditional tense for regular verbs, you keep the entire infinitive—in this case, donar (to donate)—and add the conditional endings directly to it. The ending for tú (informal "you") is -ías, giving us donarías.

How do we know this means "you would donate" if the word tú isn't in the sentence?

The ending -ías on a conditional verb is only ever used for tú (informal you). Because the verb ending makes the subject perfectly clear, Spanish speakers typically leave the pronoun out unless they want to add extra emphasis.

Why does this sentence use al instead of a el before hospital?

Whenever the preposition a (to) is followed directly by the masculine singular article el (the), they must combine into the single word al. Since hospital is masculine, we have to say al hospital.

Could I say muchos dineros to mean "a lot of money"?

No, just like in English, the concept of "money" (dinero) is generally treated as an uncountable singular noun. Therefore, the adjective mucho stays in its singular, masculine form to match it.