--= Scoreboard Timer: =--

• You literally just count up by 1, detect a score, and add to the next value

Here's an example:

Setup:

scoreboard objectives add Timer dummy

Looping:

scoreboard players add $Ticks Timer 1
execute if score $Ticks Timer matches 20.. run function namespace:second

Second:

scoreboard players set $Ticks Timer 0
scoreboard players add $Seconds Timer 1

(Copy and Paste Extract from Knowledge Base https://discord.gg/xpNJdH9)

(Raw Paste & More https://github.com/SheepCommander/KnowledgeBase/tree/main/1.16.4/faq/scoreboard-timer)