Questions & Answers about Ljeti sušilica na balkonu brzo suši rublje.
Ljeti is an adverbial form meaning “in (the) summer / during summer”. It’s derived from the noun ljeto (summer), but it behaves like an adverb of time, not like a regular case form.
You use Ljeti to talk about something that happens habitually or generally in summer:
- Ljeti je vruće. – It is hot in summer.
- Ljeti sušilica na balkonu brzo suši rublje.
u ljeto is possible but much less common, and it sounds more like “into the summer / at one particular summer”, often in more literary contexts or when contrasting seasons.
In everyday speech, for general, repeated actions in that season, Ljeti / Zimi / Ujesen / U proljeće (note: u proljeće is the usual form) are standard. Here Ljeti is the natural choice.