Some and any can be used when:
The exact number is not known.
The exact number is not important or relevant.
Some - is used in positive sentences, offering, & requests
I am going to buy some cake for tonight.
We have to make some phone calls.
They have to bring some money, so they can pay me.
Can I have some more tea, please?
Any - is used in negative sentences, to state something doesn't matter
I am not going to buy any cake for tonight.
We do not have to make any phone calls.
They do not have to bring any money.
Some and any are used to state the quantity, amount of something. When using some or any the exact number is not stated. Some and any are quantifiers.