Exodus 12:38 New English Translation

³⁸A mixed multitude^[a] also went up with them, and flocks and herds—a very large number of cattle.^[b]

Exodus 12:38 tn The “mixed multitude” (עֵרֶב רַב, ʿerev rav) refers to a great “swarm” (see a possible cognate in 8:21 [17]) of folk who joined the Israelites, people who were impressed by the defeat of Egypt, who came to faith, or who just wanted to escape Egypt (maybe slaves or descendants of the Hyksos). The expression prepares for later references to riffraff who came along.
Exodus 12:38 tn Heb “and very much cattle.”

New English Translation (NET)