i'm not an expert. but here it is :
memory use 757 ( allocated memory) ( 36 % free ) ( minecraft server have max memory set by player from the start.bat file. allocated memory (by java from the max memory ), and used memory ( from the one allocated )
Threads: Cpu threads (from
HyperThreading technology ,multitasking, i core can do 2 threads, a quad core has 8 threads, )
avg tick: ( minecraft lag is calcualted on tick per second. normal is 20 TPS. you have there the average tick in MS, for example mine is 9-14 ms. if you have high. like 200+ ms, you have lag )
avg sent
avg rec : packets sent from server to client in kb ( for a high user server you need some good internet band. A player can get up to 1 MB/s in a high populated machine area. usually redpower microblocks use a lot of band )
LVL -1 tick,chunk chake. etc: ( each map has a level numbar, each map is made with chunks ( if i remember correctly its a 16x16 area here is a picture of one :
http://images2.wikia.nocookie.net/_...ft/images/thumb/e/ec/Chunk.png/89px-Chunk.png ) The server loads chunk's in vecinity of the player, by using ram, this is also set by player in the server.proprietis using view range setting. a smaller view range like 6. will make you not see that far,so the server loads less chunks.
server also use ram when the player explores the world. The map is not fully generated when the server creates it, it generates itself when players explores.
the other numbers like drop. vec3. i have no idea what are they
Also what you have there is called a GUI. i recommend you turn that off. ( edit start.bat and add nogui at the end of the command line ) that GUI has bin reported to use memory and make lag.