The expression “X को लेकर” in Hindi literally means “taking X”. It consists of the postposition को and the conjunctive participle लेकर (from लेना, “to take”). Of course, this can be used literally, as in वह पुस्तकों को लेकर घर गया (“He took the books and went home”).
However, this expression is commonly used to mean “with respect to X”, “regarding X”, “about X”, “concerning X”, “related to X”, etc.
It can be used adverbially, as in the following examples:
विशेषज्ञ ने ग्रामीण इलाकों में शिक्षा सुधारने को लेकर कई तरह के सुझाव दिए – “The expert gave several suggestions about improving education in rural areas”.
वह कल रात को हुई घटनाओं को लेकर विवाद में फंस गया – “He got stuck in a dispute regarding the events that occurred last night”.
This expression is also used in phrases:
प्रधान मंत्री की घोषणा को लेकर प्रश्न – “A question about the Prime Minister’s announcement”.