What does “sentir” mean in French?

Sentir covers smelling in both directions, just like English “smell”: je sens le café is “I can smell the coffee,” and ça sent le café is “it smells of coffee.” The verb pairs up neatly with bon and mauvais — sentir bon is to smell good, sentir mauvais to smell bad — and that pair is the one worth reaching for first.

Made reflexive, se sentir switches over to feelings: je me sens bien, “I feel fine”; je ne me sens pas bien, “I don’t feel well.” One root, then, gives you both the nose and the mood — worth noticing early, because the two uses look identical on the page.