Let me preface this with "I BELIEVE" (I'm still fairly new to the mech keeb world so I may be incorrect.)
the 3 on the left of the spacebar are standard 1.25u, 6.25u spacebar, 1.5u ctrl and 1.5u alt on the right and a 1.75u right shift. *(Figured I should edit this as you said you were still new, a 'standard bottom row' would be 6.25u space bar with 3 1.25u modifers on the left and 4 1.25u modifiers on the right and a 2.75u right shift.) From...