What does quandō̆quidem mean in Latin?

quandō̆quidem, a conjunction, means “since, since indeed, seeing that, inasmuch as, because”.

How do you pronounce quandō̆quidem?

In classical Latin, [kʷanˈdoː.kʷɪ.dẽː]; in ecclesiastical (church) Latin, [kʷanˈdɔː.kʷi.dem].

since, since indeed, seeing that, inasmuch as, because
MENAECHMVS Līberem ego tē? MESSENIO Vērum, quandŏquidem, ere, tē servāvī... MEN. Quid est?MEN. I should free you? MES. Sure, seeing as I saved your life, master... MEN. What's that?c. 200 BCE, Plautus, Menaechmi 5.7.line 1024 (trochaic septenarius)
PAMPHILUS: Atque hoc cōnfiteor mihi / iūre obtigisse, quandōquidem tam iners tam nūllī cōnsilī sum.PAMPHILUS: And yet I admit that this has happened justly to me, since indeed I am so lazy, so lacking in good judgment.166 BCE, Publius Terentius Afer, Andria 607–608

quandō-quĭdem (o scanned short, Verg. E. 3, 55; Lucr. 2, 980), adv.,

I. since indeed, since, seeing that (class.): quandoquidem tam iners, tam nulli consili sum, Ter. And. 3, 5, 2; 3, 2, 7; id. Ad. 5, 8, 33; id. Eun. 2, 3, 82: quandoquidem tu istos oratores tantopere laudas, Cic. Brut. 44, 163: quandoquidem id tale esse debet, ut, etc., id. Fin. 5, 13, 37; 5, 23, 66; Liv. 8, 33: haec detur cura censoribus, quandoquidem eos in re publicā semper volumus esse, Cic. Leg. 3, 20, 47; id. Or. 31, 112; id. Phil. 2, 3, 6; id. de Or. 3, 14, 54: dicite, quandŏquidem in molli consedimus herbā, Verg. E. 3, 55: quandŏquidem totis mortalibus adsimulata, Lucr. 2, 980; Juv. 1, 111; 10, 146; 13, 129.

Univerbation of quandō (“when, now that”) + quidem (“restricting particle”).