If I drop out, can I restart my Master's degree in the future?
Possibly

but it sounds like you haven't officially "dropped out" yet, so there is another better option if you'd like to return

Take A Leave Of Absence 

Most universities offer students the ability to take a semester to a year off and return without reapplying.  It's usually referred to as a Leave of Absence.  You'll have to talk with someone in the administrative office of your university, and possibly someone in your department.

It's more common than you think.  Some students do it to deal with medical issues, but many do it for the reason you're considering dropping out.  Getting a degree can be overwhelming sometimes, and if you're struggling early on, sometimes a break can help you re-group and catch up.

Universities understand that sometimes a student can get overwhelmed, before dropping out, see what other options there may be to give you time to catch up and improve your study skills.