For Mass Effect: Infiltrator:
Throughout each mission, the player can collect intel points which can
be uploaded to Mass Effect 3's Galaxy at War system to increase the
Galactic Readiness rating or for in-game credits.
You can either promote a lvl 20 character and increase galactic readiness. Completing missions increases galactic readiness which determines at what strength your assets are at the final mission. A promoted level 20 character will be added as a war asset.
But as the commenters pointed out, other questions provide a more detailed response
here, here, and here.