Learn Russian: Сейчас скорая везёт пациента в больницу. - The ambulance is taking the patient to the hospital now.

Везёт is the unidirectional verb for transporting someone or something by vehicle. Because this action is happening сейчас (right now), the ambulance is making a single, one-way trip to a specific destination. If it were a general, repeated habit like 'Ambulances transport patients', you would use the multidirectional verb возит.

Why is the word for 'ambulance' just скорая, which looks like an adjective?

Скорая is indeed the feminine adjective for 'fast' or 'quick'. It is a shortened version of the full phrase скорая помощь (first aid / ambulance). In everyday spoken Russian, people simply use the adjective скорая on its own as a noun to mean ambulance.

Why does пациента end in '-а' if it is the direct object?

Since the patient is the direct object being transported, the word must be in the accusative case. For masculine nouns that are 'animate' (living people or animals), the accusative case takes the exact same endings as the genitive case. Therefore, the dictionary form пациент adds an '-а' to become пациента.

Why is it в больницу and not в больнице?