Sure thing there Natalie, thanks for the question. This is a tough one. What you need to understand first is that we are dealing with Leaving Group conversions, so if you are confused about anything that's going on or the explanation, that would be the best place to start by watching these videos:
https://www.clutchprep.com/organic-chemistry/leaving-group-conversion specifically where we talk about the use of Sulfonyl Chlorides. In the first step we are converting the primary alcohol into our Tosylate, this is now an excellent leaving group.
Now you may be wondering why it doesn't react with the other alcohol as well? Well, the answer is that it will however we know that it is going to prefer to react with the primary instead because this will suit us better for the next step of our reaction which is Nu Attack of that group through an Sn2 mechanism like it states in the question. Also there must be only 1 equivalent given, if it stated 2 equivalents that would be a different story!
From there, in our next step we are reacting with base and by the looks of the Molecular Formula of our product it seems like we are only getting one O in it, with also an IHD of 2. Refer back to these videos if you are confused:
The way that that we can accomplish that is as follows: our base is going to rip off our acidic H on our secondary alcohol. The ion that we form will then do a Nu Attack on the carbon that bears our OTS leaving group which allows us to form a 5-membered ring as our product.
I hope this makes sense!