Pub/Sub dumb question regarding publish and send

This should be obvious, but I cannot find anywhere in the Pub/Sub documentation to verify my guess:

In GCP Pub/Sub, does the verb "publish" mean "for an originator to send to a Pub/Sub topic", and does the verb "send" mean "for Pub/Sub to send from a topic to the receiver in a subscription"?

The following summary statistics are provided "out of the box" by Pub/Sub, but I am not 100% sure what I'm looking at.

If I am incorrect, please correct my understanding, or point me to some documentation. I couldn't find anything to explain this super-basic definition.

Solution

These graphs each correspond to a metric available in Cloud Montioring:

"Publish" is an aggregation over topic/message_sizes, which is the number of messages published.
"Sent" corresponds to subscription/sent_message_count, which is the number of messages sent by Pub/Sub to the subscribers.
"Ack" corresponds to subscription/ack_message_count, which is the number of messages acknowledged by subscribers.