What is Mild olive oil and what can I use instead?

There is also a product called Light Olive Oil. I usually recommend this to friends who don't like strongly flavored olive oil. It has the same fat profile of course, but has a very mild flavor.

SillyBee's response is correct -- hope this helps!

There are some olive oils that are stronger tasting. For example, they have grassy undertones or a spicy aftertaste. Usually they're used for dipping bread or as a dressing or drizzle. It sounds like the author doesn't want you to use an olive oil where a particularly strong flavor will overpower the crust and peaches. Looks like you're good with either mild olive oil or vegetable oil.