More or less means ‘mostly’, ‘nearly’ or ‘approximately’. We use it in mid position (between the subject and main verb, or after the modal verb or first auxiliary verb, or after be as a main verb). It is slightly informal:
We had more or less finished, so we decided to go for lunch.
We commonly use it after numbers and measurements:
It should cost you about £100, more or less.
We don’t normally use more or less before people’s ages: