duften
to smell fragrant
To give off a pleasant, fragrant smell.
Im Frühling duften die Blumen im ganzen Garten.
In spring, the flowers smell fragrant throughout the whole garden.

to smell fragrant / be great
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to smell fragrant
To give off a pleasant, fragrant smell.
Im Frühling duften die Blumen im ganzen Garten.
In spring, the flowers smell fragrant throughout the whole garden.

The verb 'duften' (to smell fragrant) is directly related to the noun 'der Duft' (a pleasant smell/fragrance). When something 'duftet' (smells fragrant), it gives off a 'Duft' (fragrance).
Der Duft von frisch gebackenem Brot ist herrlich.
The smell of freshly baked bread is wonderful.
To describe what something smells like, you use the preposition 'nach' followed by the dative. The structure is: Etwas duftet nach etwas (something smells of/like something).
Die Seife duftet nach Lavendel.
The soap smells like lavender.
The meaning 'großartig' (great) or 'super' is colloquial and is used rather rarely today. It can sound a bit old-fashioned, but it is still sometimes used ironically.
Ein Ausflug ans Meer? Das finde ich eine dufte Idee!
A trip to the sea? I think that's a great idea!
You can easily distinguish the two meanings: if the subject is something that can have a smell, such as food or flowers, the meaning is about scent. If the subject is a person, idea, or thing being evaluated, the colloquial meaning 'toll' (great) is meant.
Der Kuchen in der Küche duftet wunderbar.
The cake in the kitchen smells wonderful.
super
'super' and 'duften' can both express enthusiasm, but they are very different in how they are used. 'super' is a normal, very common word for something that is very good. 'duften' in the sense of 'being great' is colloquial and sounds rather old-fashioned today. Also, 'duften' usually means that something smells pleasant. So 'super' is a better fit in almost all everyday situations when you simply want to express praise.

Mein Opa sagt noch: „Der Plan duftet“, wenn er ihn richtig gut findet.
My grandpa still says, “Der Plan duftet,” when he thinks a plan is really good.
Deine Idee für den Ausflug ist super.
Your idea for the trip is great.