Hi @Gail26
Welcome to the community!
There is no native function in the phone to block phone numbers, however you can send a caller straight to voicemail to avoid receiving the call.
From your Home screen, tap the Application screen icon > Find and tap Contacts > Tap the contact that you want to forward to voicemail, then tap the Edit contact icon (icon with a contact and a pen) > Tap the menu button (three vertical dots), then mark the All calls to voicemail checkbox > Tap Done / SAVE.
Alternatively, you can download and install an app from the Play Store to perform this function instead.
Good luck 
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