How can I understand the concept of seven heavens in Islam?

We have been told about seven heavens in the Quran. Quran mentions it in 71:15 > Do you not consider how Allah has created seven heavens in layers. Also the Prophet (PBUH) went through all these heavens one by one when he was ascended to the skies. He was accompanied by Angel Gabriel in his journey and even Gabriel had to leave him alone on his last part of journey because Jabiel was not allowed to go above certain heaven (sky). **My question is, does Heaven in Quran mean Sky? What does it refer too? How can I visualize seven heavens? Can I take that as scientific statement?**