A split shift is a type of shift-work schedule where a person's work day is split into two or more parts. A regular break for rest or to eat meals does not count as a "split".
For example, a person may work from 05:00 to 09:00, take a break until 14:00 and then return to work until 19:00. This kind of pattern is especially common for people such as public transport employees (where it is advantageous to have additional staff working during traditional rush hour times) or bar staff that work at lunchtimes and during the evening.