If a certain person is harassing you with calls or messages, it's perfectly normal to block them from your Apple Watch. It's not ideal, but it helps you regain control of your device and protect your privacy. If you're not sure whether a contact has blocked you, there are some easy ways to check on this.
Managing blocked contacts on the Apple Watch requires access to a paired iPhone. Your Apple Watch mirrors the settings of your iPhone, so if you block someone on your iPhone, they will be blocked on your Apple Watch as well. To block a caller on your Apple Watch, open the "Watch" app on your iPhone, select the "Phone" or "Messages" app, then tap the name of the contact you want to block. You can also block unknown calls (those that don't appear in your contacts list) from the 'Silence Unknown Callers' feature on your iPhone.
Another way to check if you've been blocked is by checking delivery notifications beneath your iMessages on the iPhone. If you're blocked, the delivery notification won't show up beneath the blue iMessage text bubble. You can also look for green text bubbles, which indicate that the message was sent as SMS and not iMessage.
If you change your mind and decide to unblock a contact, you can do so on the iPhone by opening the 'Settings' app, then tapping 'Phone' or 'Messages'. Select the contact and swipe left. It will take a few minutes for the process to complete.