Learn Portuguese (Portugal): A casa cheira a café.

In Portuguese, the verb cheirar (to smell) is followed by the preposition a when describing what something smells like. Even though English uses "of" or "like", you must use cheirar a, not cheirar de.

Can cheirar also mean the action of smelling something with your nose?

Yes! The verb cheirar can mean both giving off a scent (like the house in this sentence) and the physical action of sniffing. For example, eu cheiro o café means "I smell the coffee." You have to rely on context to know which meaning is being used.

Why isn't there a definite article before café? I expected ao café.

We don't use the definite article o here because we are talking about the general scent of coffee, not a specific batch. If you were referring to a specific coffee, the preposition a would combine with o to make ao (for example, cheira ao café que fizeste meaning "it smells like the coffee you made").