The card reads, "Instead of revealing an order during the operations phase, you may discard this card to resolve an Advance Order in any system containing at least 2 of your units."

Is this card basically an advance order? Like can a player have all their tokens in other systems but play this card and basically use an advanced order in a system where they had no tokens? Or is this basically allows the player to resolve an advance order that may be on the bottom of the stack instead of being attacked first?

Yes to both. Plus, this allows you to resolve a Strategize order three times in the same game round. How you use it depends on your strategy.

How does that allow 3 Strategize orders ? I see it as 3 Advanced Orders are possible not Strategize .

If you mean, can you instead treat the card as an advance order to discard it onto your event deck, then no. It doesn't give you an order token to let you do that.

Also, you have to be able to actually play an order. When your turn comes, you must have an order token on top of an order stack somewhere on the board. You don't do anything to the order token, but you must have it sitting there. If all your orders are still buried, or you have already used up your order tokens that turn, you can't use Mob Up.

Agreed, you can use it as above described, save for seting it aside on your event deck