Usually, a simple PBR material feature texture maps for:

Color (Diffuse)

Roughness

Normal (Bump)

You must connect each map to the corresponding input socket of a

Shader, to produce a realistic material. The best Shader for PBR

materials is the Principled BSDF (Figure 5.15).

Figure 5.15 - Principled BSDF

Before we start using PBR materials, you have to find some of those

special sets of textures. A PBR material usually comes with multiple of

those maps available. Several online libraries offer free PBR materials.

Some of the best sources for PBR materials:

ambientcg.com

texturehaven.com