What size is M in UNIQLO?

Excuse me, could you please clarify the sizing for UNIQLO's clothing? Specifically, I'm wondering about the size M. Is it a standard medium size that would fit someone of average build, or does it vary depending on the style or type of clothing? I'm trying to ensure that I order the correct size for my needs, and I'd appreciate any guidance you can provide. Thank you in advance for your assistance.