Can you please tell me what this sentence means?

"Flight", as used here, means a journey in an aircraft. Every flight that departs from and arrives at an airport is given a number. Giving a flight a number avoids confusion when someone wants to refer a certain journey. It is much more convenient to say, "What time does Flight 401 arrive?" than to say, "What time does that flight from Seattle, via Portland and Saskatchewan, arrive?"

The aircraft that will make the journey, in this case, will be one of the type L-1011. Every flight is made by an aircraft that has an identification number that is allocated to it by the airline that owns it. Again, this saves time. Plane #310 is the plane that will be used for Flight 401.

Your sentence means this: the journey that is numbered Flight 401 on the timetable will be made by an aircraft with the maker's model number of L-1011. We (the airline that owns that aircraft) have called that particular aircraft #310, because it is the 310th plane that we own.

Plane #310 is the airline's number for the plane, which also carries a manufacturer's model number of L-1011. The Flight number is 401. /// The airline owns at least 310 planes. Plane #310 is a (Boeing) model L-1011, and it is currently covering today's flight # 401. (401 is a flight number assigned to the trip between city A and city B. )