Chrome profiles are a great way to keep separate sets of bookmarks, cookies, themes, and settings. They’re very useful in the following cases:

You need to have clearly separate your “work” from your “personal” online identity (also called online persona).
You are an IT manager or IT admin and you need to log into end-user accounts (i.e., their Gmail account). In this case, it is very important to create a separate Google Chrome profile for each of your users (the other approach is to *always* use Gmail Chrome incognito window)
You are assistant and you need to log into your’s boss account. In this case, create two Google Chrome profiles: one for you and one for your boss’s online identity
You need to have different online identities for privacy reasons
There are multiple people use Chrome on the same device. So you will have profiles like “mom”, “dad”, etc.
If you are MSP (Managed Service Provider), then it is wise to have a dedicated Google Chrome Profiles for each of your clients when trying to login to their servers. This will ensure that some sensitive data (from cookies, browsing history, etc.) is not leaked between your customers.
You can multiple “online” identities (Google accounts, Dropbox accounts, etc.).

Keep in mind that anyone using Chrome can switch to any other profile that’s signed in, so only share your device with people you trust.

Create a Chrome profile

Switch between Chrome profiles

In Chrome menu, click on the People menu
Select the profile you’d like to switch to.
When you sign in with your Google account, all of your bookmarks, history, passwords, and other settings will be automatically loaded, so you can get the same Chrome experience every time you log in.

The advantages of separate Google profiles vs. multi-account access in Chrome are explained in the support note called The advantages of separate Google Chrome profiles vs. multi-account access in Chrome