An "entry" is a 'point' or a 'chance of winning'.
For example,
1 entry = 1 chance of winning
10 entries = 10 chances of winning
....
.....
....
300 entries = 300 chances of winning
Having more entries equals a greater chance of winning. Because we use random-weighted drawing for selecting the lucky winner(s), having more entries is like legally stuffing the ballot box aka higher chance of winning.