IPA: /ˈsɛk.ənd.li/
KK: /ˈsɛkəndli/
In the second position or place; used to introduce the second point in a list or argument.
Firstly, we need to gather all the materials; secondly, we can start the project.
Secondly → It is formed from "second" (from Latin "secundus", meaning second or following) and "-ly" (a suffix used to form adverbs). The word "secondly" means in the second place or as the second point in a sequence.
Think of the word 'second' which means the next in line, and remember that 'secondly' refers to the second point in a list or argument.