Hide links

Hello, I never used wordpress, and a friend have some probleme, I search about my probleme, but didn’t find (or didn’t understand the answer)
(french speaker here :D)

Ok, so my probleme is that she had three main links and one of it is to show her work, and she has a lot of links (1,2,3,4..etc) that show everytime, and I wanted to hide it, and show the “1,2,3,4) links only when you click on the main link “work”

I hope you understood my problem… The thing is, there is only “Pages” that was created, and the “1,2,3,4..” pages are children of “work” so it show correctly, but it doesnt hide….

Thank you for your time… here’s the link if you wanna understand what I said ^^