Typically, it is the part that extends beyond the building wall, aka tail of the rafter. It creates the area where you can stand under the edge of the roof when it rains.
A roof overhang is generally just called a roof overhang unless you are referring to a specific part of the overhang.
There is no "standard". It depends on the construction, dimensions, and the overall goal/intent of the roof overhang.
under the overhang of the roof
A synonym for eaves is roof overhang.
eave The overhanging edge of a roof.
Eaves, meaning the projecting overhang at the lower edge of a roof. In a sentence: The eaves of the roof will be 0.5m
A shelter can be anything from an overhang roof to an actual simple building.
A rake board is a part of the roof of a house. The rake board is the diagonal board on the side of the roof's overhang.
Most likely it would be referred to as the overhang.
The eaves are the edges of the roof which overhang a building.
This question's relevance does not mention size, span, eave overhang pitch nor complexity of the job.
Here's my suggestion: Buy a set of brass tacks and a roll of aluminum screening from a hardware store. Cut the screening into strips eight inches wide and tack them over the gap in the roof overhang, where the birds are getting in to nest. That's it.