They review your lease and explain every clause before you sign. The deposit can reach 3 months' rent, the landlord may ask for up to 3 months' rent in advance on top, with no more than 6 months in total. The tenant's notice period is generally 3 months, to be checked in the contract.
They also help you prepare your file, understand the CPR number and MitID with no promise on timing, and record defects in the move-in report within 14 days.