for understanding this command draw a database table,write 0,1,2_3...beside uid column,then u wil notice that count 3 is uid 4,since uid starts from 1 and count starts from 0,so lets say we write count for starting position uid 0. 1 1. 2 2. 3 3. 4
As in almost every programming language indexes starts from Zero('0') index, 3 denotes the fourth('4') node/element in array/collection. In this case 4th row of the table. So 'limit 3, 4' will return rows starting from 'Row 4th' up to 'Row 8th'. First value denotes the starting and second values tells how many rows to fetch.