What does Shira mean?
Modern Hebrew shira, 'song, singing, poetry' (root sh-y-r). A popular contemporary given name; a concrete noun with no theophoric element.
What does Yael mean?
From Hebrew ya'el, 'ibex' — a nimble, sure-footed wild mountain goat. The same name as the heroine Jael, who killed Sisera (Judges 4-5). A concrete noun; the 'strength of God' gloss seen on some sites is not the standard derivation.