I want to sync music to my iPhone 5s but I don t know what I am doing?

I just bought an iPhone 5s and I am trying to sync music onto it. I have a few apps like Netflix, Hulu, and Facebook, nothing major and a few photos. I am using my wife’s laptop but we both have 2 different accounts on the one laptop, hers being the admin account. She has her own iTunes account and her own iPod shuffle.

I installed iTunes on my computer account and put music on it and linked it to my own iCloud account. When I plug in my iPhone and I try to manually manage music, a window pops up and says,

“ The iPhone “My iPhone” is synched with another iTunes library on “My Wife’s Computer”. Do you want to erase this iPhone and sync with this iTunes library?
An iPhone can be synced with only one iTunes at a time. Erasing and syncing replaces the contents of this iPhone with the contents of this iTunes library. ”

What does this mean? If I press the “Erase and Sync” button, what will happen? Is my iPhone permanently attached to my wife’s iTunes or computer?

Can you have 2 different iTunes accounts on 1 computer?

Thanks for all information you can give me, I am new to this whole Apple thing.

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