Summarize the following:
Tap the person silhouette app icon. You'll usually find this on your Android's main screen or in the Apps menu. It's in the top-right corner of the screen. A drop-down menu will appear. This option is in the drop-down menu. It's near the top of the page. This option is near the top of the page. If you want to select a contact to block, tap Select form people, if you want to enter a number to block, tap Add number. If you are blocking a contact, tap the checkbox next to the contact you want to block.  If you selected "Add number", enter the number that you want to block. Doing so will add the number to your phone's block list. You should no longer receive calls from the blocked number.

Summary:
Open your Android's People app. Tap ⋮. Tap Manage contacts. Tap Blocked contacts. Tap Add. Tap Select from people or Add number. Tap the checkbox next to a contact or enter a number. Tap Save.