"In our hands" definition: "Under one's control or influence; in one's possession."
Outscore and have a better GD and win all our games. But if Leicester win all there games, which is NOT, I repeat, not, in our control, and it matters not if we win all our games or have a better GD.
Now, we know that LCFC are Shite for form and will drop points, but that's assuming we won't. All we have in our hands is our own point tally, it's in Leicesters hands since they have 3 points advantage over us. When they feck it up by losing enough matches and we have more points than then, then it is totally..."in our hands."
If you don't understand the phrase in our hands after that, then it's fine, carry on.