Welcome to the forums, Chrischu.
No, "tens of thousands" doesn't mean "many", Chrischu. It means thousands above 10,000. For example, if you said "My vehicle is worth tens of thousands", I would know that its value is anywhere between $10,000.00 and $99,999.00. 100,000 to 999,999 would be "hundreds of thousands". Anything under 10,000 would be "thousands".