Lately means in the recent past — over the last few weeks or months. Have you seen her lately? It has been very quiet lately.
It goes almost exclusively with the present perfect or present perfect continuous, because it describes a period running up to now: I have not seen him lately, not I did not see him lately. Recently does the same job and is commoner in writing; lately is a shade more conversational and is slightly more likely to appear in a question. Note that lately is not the adverb of late: arriving late and arriving lately are entirely different claims.
lately is a period of time.
Middle English
lately
English, today
lately
From Middle English lately, latly, equivalent to late + ly. Compare Old English lætlīċe (“slowly, tardily”), Middle Low German lātlîk (“careless, slack, sloppy”).
Etymology from Wiktionary, CC BY-SA