Problem with the roof

[DarkKnight]

I have a flat roof with an unfinished cement-like surface, and I’m concerned about water pooling on it and potentially getting absorbed over time. I’m looking for a suitable finishing solution that can prevent water from standing on the roof and ensure it remains waterproof. Could anyone recommend materials or methods to properly seal or finish the surface to improve water drainage and prevent absorption? I'd appreciate any advice on long-lasting, effective options!

Kindly also guide if this project can be completed without professional help. The roof is easily accessible.