What does the "processing pending approval" status mean for my Thai eVisa application?

That can vary a lot depending on where you apply.

In my case, both applications required additional documents or written clarifications.

In Penang (Malaysia), I waited 10 days, submitted the requested documents, and the application was eventually cancelled because it had been submitted while I was still in Thailand.

In Vietnam (Ho Chi Minh City), additional documents were also requested, but the application was approved after 5 working days, which seems fairly normal there.

So I’d say 5 working days is the minimum, but more time is definitely possible — it really depends on where you apply.

Normally, the processing time is 10–15 business days, depending on the Thai embassy or consulate handling your visa application.

On day 3 or 4 I received a notification for clarification and more info as did my friend who applied the same day as I. Then a week later, she was approved and I am still waiting. Be patient. I am trying to as well

Reading your previous post, are you in Vientiane waiting? I paid my application on Tuesday and was approved Yesterday.