pꜣ(“the”) + sbꜣ(“star”) + ḫꜥ(“appearing”) + n(“in”) + nwt(“city”), thus literally ‘the star appearing in the city’, a reference to Thebes.
Greek Ψουσέννης(Psousénnēs) reflects the later (Demotic-era) shift of /ḫ/ → [ʃ] in [pəsiβʃəʕənˈneːʔə]. The preposition m appears as n due to assimilation with nwt.
Ranke, Hermann (1935) Die ägyptischen Personennamen[1], volume 1, Glückstadt: Verlag von J. J. Augustin, page 117.1
Leprohon, Ronald (2013) Denise Doxey, editor, The Great Name: Ancient Egyptian Royal Titulary, Atlanta: Society of Biblical Literature, →ISBN, pages 139, 141, 143
von Beckerath, Jürgen (1984) Handbuch der ägyptischen Königsnamen, München: Deutscher Kunstverlag, →ISBN, pages 98–100, 253–256