m-of-n is just a common way of describing multi-sig set ups. The m stands for how many signatures you need, and the n stands for the total number of cosigners. For example, in a 2-of-3 multi-sig, there will be 3 cosigners, with the signatures of any 2 of them needed to spend the coins.
This is what I initially thought too, I just didn't want to be confused so I asked for a clarification which I got with this one, thanks. Can you set the minimum signature to open the wallet? If so, that means that you can set it as 3 of 3?
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Although P2MS is very rarely used now, the script used in P2MS is the same script which is used in newer P2SH/P2WSH multi-sig addresses, so still worth a read.
I guess, I'll give it a go seems like a really good read too, I skimmed the contents and I hope that I can understand the technical terms, I'm not that good with unknown stuff.