First, the location of the fonts folder which you placed needs to change, you need to place your fonts under the resources folder, the resource folder should be under clientlibs
You can refer weretail:

Sample code:
font-family: SlatePro-Bk;
src: url("../resources/fonts/we-icons.1.0.0.woff") format("woff");
}
you can either use the Maven project to import fonts files to AEM or a temporary solution is export clientlib as package and add font files then import it to AEM.