OET interlinear PSA 51:5

uW Translation Notes:

Note 1 topic: figures-of-speech / metaphor

הֵן

(Some words not found in UHB: that/for/because/then/when transgressions_of,my I know and,sin_of,my [is]_before,me ever )

David is using the term Behold to focus attention on what he is about to say. Your language may have a comparable expression that you can use in your translation, here and in the next verse.

Note 2 topic: figures-of-speech / explicit

בְּ⁠עָו֥וֹן חוֹלָ֑לְתִּי וּ֝⁠בְ⁠חֵ֗טְא יֶֽחֱמַ֥תְ⁠נִי אִמִּֽ⁠י

(Some words not found in UHB: that/for/because/then/when transgressions_of,my I know and,sin_of,my [is]_before,me ever )

David does not mean that his mother conceived him as the result of a sinful act. Instead, he means that as a human being, he has been characterized by iniquity and sin for his entire life. You could indicate this explicitly in your translation if that would be helpful to your readers. Alternate translation: [I have been iniquitous since I was born; indeed, I have been sinful from the time my mother conceived me]

Note 3 topic: figures-of-speech / activepassive

בְּ⁠עָו֥וֹן חוֹלָ֑לְתִּי וּ֝⁠בְ⁠חֵ֗טְא יֶֽחֱמַ֥תְ⁠נִי אִמִּֽ⁠י

(Some words not found in UHB: that/for/because/then/when transgressions_of,my I know and,sin_of,my [is]_before,me ever )

The expression was born is a passive verbal form. If your language would not use that form, you could express the idea in active form or in another way that would be natural in your language. Alternate translation: [I was in iniquity when my mother gave birth to me; indeed, I was in sin when my mother conceived me]