I believe both are correct. In American English, "weekend" is said as "on the weekend" or "on weekends", while in British English it is said "at the weekend" or "at weekends".

Yes Trixie is right. To be 100% accurate, we say AT the weekend as we are referring to a specific period of time. But in everyday English the use of ‘on the weekend’ is becoming more heard too

Szia, Zoltán! Hogy vagy? The correct saying would be: "I often visit my uncle on the weekends." (We do activities "on" the weekends, not "at".) *Fun fact: I live in the U.S., but my anyuka liked the name Zoltán so much that she named our macska Zoltan. Zolie for short! It is a fantastic name. I hope this suggestion helps. ;-)

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