Exodus 7:5 New English Translation

⁵Then^[a] the Egyptians will know that I am the Lord when I extend my hand^[b] over Egypt and bring the Israelites out from among them.”

Exodus 7:5 tn The emphasis on sequence is clear because the form is the perfect tense with the vav consecutive.sn The use of the verb “to know” (יָדַע, yadaʿ) underscores what was said with regard to 6:3. By the time the actual exodus took place, the Egyptians would have “known” the name Yahweh, probably hearing it more than they wished. But they will know—experience the truth of it—when Yahweh defeats them.
Exodus 7:5 sn This is another anthropomorphism, parallel to the preceding. If God were to “put” (נָתַן, natan), “extend” (נָטָה, natah), or “reach out” (שָׁלַח, shalakh) his hand against them, they would be destroyed. Contrast Exod 24:11.

New English Translation (NET)