Here's what each message status indicates:
Sending
Sent
Delivered
Read
My message is stuck as 
Sending or spinning, what do I do?
Signal uses your phone's internet connection for all private communication. The most common reason why you can't send messages is that you are not connected to the internet or have restricted Signal's internet access.
- Confirm you are connected to the internet.
- Re-enable permissions and settings on your phone.
- Disable or modify settings for your third-party app, VPN, or firewall that is limiting Signal's connection to the internet.
- Scroll up through the conversation to see if there is a large attachment that is trying to send and delete the message.
- For insecure SMS/MMS, follow steps below.
See additional steps for:
Android
How do I communicate privately?
Signal uses your phone's internet connection for all private communication.
- Check permissions and settings as listed in the steps above.
- Confirm your contact is also using Signal.
- Check how your contact's phone number is formatted in your Android phone. Make sure the phone number includes a country code and/or area code. See the steps on the support page for editing your contact's number.
Switch to a different SMS/MMS app.