He assumed his brothers would understand that God was using him to deliver them, but they did not.
Berean Standard Bible (BSB)
He supposed that his brothers understood that God, by his hand, was giving them deliverance; but they didn’t understand.
World English Bible (WEB)
For{G1161} he supposed{G3543}{(G5707)} his{G846} brethren{G80} would have understood{G4920}{(G5721)} how{G3754} that God{G2316} by{G1223} his{G846} hand{G5495} would deliver{G1325}{(G5719)}{G4991} them{G846}: but{G1161} they understood{G4920}{(G5656)} not{G3756}.
Strong's King James
(25) Now he thought that his brothers understood that The אֱלֹהִים Elohim was giving them salvation through his hand but they didn't understand.
The F.O.G
The F.O.G Message
and he was supposing his brethren to understand that God through his hand doth give salvation; and they did not understand.
Young's Literal Translation