As we talked yesterday, 所 has several meanings. I was willing to tell you more details this morning.
1 there are some permanent phrases.
Examples: （means place）住所=house/home,场所=places; （means office/bureau）研究所=a place people do kinds of research there,派出所=police station; 所得税=income tax; 所有权=ownership;所以=so/so that; 所有=all of ;无所谓=doesn’t matter. I will make sentences of 所以、所有、无所谓 below.
所以：他的解释是不对的，所以我们不会相信他。His explanation is not right, so we don’t believe him.
所有：教室里所有的学生都是男生。All of the students in this classroom are boys.
无所谓：-你想吃什么，鱼还是牛肉？-无所谓。 What would you like to eat, fish or beef ? It doesn’t matter to me.
2 the grammar we discussed last night:
The structure of the sentences is 主语（You/I/He/They..）+所+ verb+的+ noun.eg:我所认识的人。
Here, 所is kind of like “被=by”.
我所认识的人=被我所认识的人=the person who is known by me=the person I know .
大家所提出的意见=the proposal we put forward.
他所说的未必确实=the words he said is not true.