We're given no dates for Léod's life, but we know that his son Eorl was born in III 2485, and that Eorl was sixteen when his father died, so it follows that Léod met his death in III 2501. We're also told that Léod was forty-two years old at that time, so it's a simple matter to calculate his date of birth as III 2459.

In Old English, éo represents a diphthong, a single vowel sound combining ay with a short o as in 'dot' or 'cloth'. So éo is pronounced somewhat like 'ayo', but as a single sound.