The contacts app on macOS is a good phone book, but also for tracking detailed personal information and connections. To add a new person to your list:
To add contacts to macOS
Open the Contacts app on your Mac from the Dock, your Applications folder, or use Command + Space to find it.
You will see a list of all your contacts. Click on one of the contacts and press the + button below to add a new contact.
You can also add contacts to the "New" hotkey Command + N.  You will see a form that you can fill in with all the contact information. The first is the name, separated by the first and the last, with the last name being optional.
Further down the list you will find that the contact card is quite thorough and gives you options of birthday, address and even multi-line personal notes about them. You do not have to fill them all. You can only add a contact with a phone or an email.
Under the name above is an option for the contact's workspace. If the contact is a company, you can select the Company check box to override these two options.
Although you can add a personal name, the company name is displayed in the contact list.
Add Contact Groups
The Contacts app contains groups for the organization. You can add a contact group in the same way you would add contacts, but by selecting "New Group" from the drop-down list.
You can also use the keyboard shortcut Shift + Command + N Add Groups Groups appear in the sidebar, and you can add an existing contact to the group by dragging the contact over it.
You can rename groups by highlighting them and pressing Enter. You can delete them by highlighting them and pressing Delete.
How to sync contacts with the iCloud
Contacts should automatically sync with iCloud as long as they're signed in to your iCloud account and have them enabled in Settings. To make sure it's enabled, open the system settings in the Dock or in your Applications folder and click on the "iCloud" settings. If you're logged in, make sure Contacts is turned on.
For everything to sync properly, you need to log in to your iPhone and other connected device and make sure you have iCloud turned on. Good. New contacts you add or edit on your phone or Mac will sync between them.
RELATED: How to set up iCloud on your Mac