What does Bilal mean?
From the root b-l-l (ب-ل-ل, 'to moisten, to wet'), understood as 'moisture, wetting, freshness'. Famously borne by Bilal ibn Rabah, the Abyssinian companion of the Prophet and Islam's first muezzin.
What does Sami mean?
From the root s-m-w (س-م-و, 'to be high, elevated'), meaning 'elevated, lofty, sublime, eminent'. Note the distinct name Sami' (سميع, 'all-hearing'), which comes from a different root (s-m-'); the two are easily confused in transliteration.