1. Like F, Greek Ypsilon has Semitic Waw as its letter of origin. The Etruscans somehow simplified the letter to V. Its Etruscan sound value was /u/; but since Latin lacked a letter for /w/, Romans used V for both /w/ and /u/. In Romance languages, V came to represent /v/ which developed from /w/; as German W – which originally was pronounced as the English letter – was pronounced /v/ since Middle High German times. At the same time, V was in German pronounced as in English, but the German Vau soon stood for /f/ again (the same is probably now happening in Dutch).
2. V represents the number 5 (five) in Roman numerals