וְאִם־אִ֥ישׁ עָנִ֖י ה֑וּא לֹ֥א תִשְׁכַּ֖ב בַּעֲבֹטֽוֹ׃
And if they are needy, you shall not go to sleep in that pledge;
(The above rendering comes from the RJPS translation, an adaptation of the NJPS translation. Before accounting for this rendering, I will analyze the plain sense of the Hebrew term containing אִישׁ by employing a situation-oriented construal as outlined in this introduction, pp. 11–16.)
In the clause וְאִם־אִישׁ עָנִי הוּא, the noun אִישׁ is not used in reference but rather as part of the predicate. (Alternatively, one can say that it refers to a category that exists only in the discourse.)
The predication uses אִישׁ to mark the attribute in question as being essential for grasping the depicted situation. (This way of using אִישׁ occurs more than a hundred times in the Hebrew Bible, even though it contributes no new information. Such usage is best explained by viewing אִישׁ as a situating noun rather than an ordinary sortal noun.) In this case, the attribute is a material fact that conditions the lender’s proper behavior.
On the gender ascription (or lack thereof), see my comment on the previous verse.
As for rendering into English, there is no warrant for rendering in gendered terms. The NJPS “If he is a needy man” is nowadays construed as gendered. The revised rendering is not a literal reproduction of the Hebrew syntax but rather adapts it for good English idiom, while being gender inclusive.