995 B
council
This was the most important Jewish Council, which was called the Sanhedrin.
cut to the heart
This is an idiom for, "overcome by anger." (See: rc://en/ta/man/translate/figs-idiom)
heard these things
This is the turning point; the sermon ends and the council reacts.
ground their teeth
This is an idiom for expressing strong anger or hatred. This can be translated as "they became so angry that they ground their teeth together." (See: rc://en/ta/man/translate/figs-idiom)
looked…up into heaven
"Looked…up into the sky". It appears that only Stephen saw this vision and not anyone else in the crowd.
he saw Jesus standing
Note that Jesus was "standing" not "sitting" at the right hand of God. It was an honor when a king would stand to welcome a guest.
glory of God
the glory or majesty of God as light. Translated as, "a bright light from God".
Son of Man
Stephen is identifying Jesus by the title "Son of Man".