Fixing Animal Entry at the Roofline
The simplest and most secure repair to keep pests out is to use 1/8 - 1/4 inch hardware cloth sold at any hardware store or building supply warehouse. The smaller the opening the more critters it will keep out.  The hardware cloth is made of galvanized wire the size is measured by the opening size (1/4 inch is how big each opening is). Purchase 8 inches more for the size you want to cover. It fastens to any surface material with any type of fastener. It cuts with metal shears so you can contour it to any shape and once installed it can be painted so it is less noticeable.   I'd start by screwing it to the bottom edge of the 2 x 10 look-out (blocking) shown in the second photo. Then screw the left and right side to the rafter above the stucco wall and the fascia board/rafter respectively. You'll have to cut around the metal flashing on the left. Install a short piece of treated lumber below the 2 x 10 blocking so the bottom edge can be screwed into place.