7 Heb “Yet forty days and Nineveh will be overthrown!” The adverbial use of עוֹד (’od, “yet”) denotes limited temporal continuation ( 728 עוֹד 1.a; Gen 29:7; Isa 10:32). rendered it as “at the end of [forty days, Nineveh will be overthrown].”
8 Heb “be overturned.” The Niphal נֶהְפָּכֶת (nehpakhet, “be overturned”) refers to a city being overthrown and destroyed ( 246 הָפַךְ 2.d). The related Qal form refers to the destruction of a city by military conquest (Judg 7:3; 2 Sam 10:3; 2 Kgs 21:13; Amos 4:11) or divine intervention as in the case of Sodom and Gomorrah (Gen 19:21, 25, 29; Deut 29:22; Jer 20:16; Lam 4:6; 245 1.b). The participle form used here depicts an imminent future action (see §37.6f) which is specified as only “forty days” away.

In other versions

Jonah began to go into the city, going a day’s journey. And he called out, “Yet forty days, and Nineveh shall be overthrown!”

Jonah began by going a day’s journey into the city, proclaiming, “Forty more days and Nineveh will be overthrown.”

Jonah set out on the first day of his walk in the city and proclaimed, “In forty days Nineveh will be demolished!”

On the day Jonah entered the city, he shouted to the crowds: “Forty days from now Nineveh will be destroyed!”

And Jonah began to go into the city a journey of one day, and he cried out and said, “Forty more days and Nineveh will be demolished!”

And Jonah began to enter into the city a day’s journey, and he cried, and said, Yet forty days, and Nineveh shall be overthrown.

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