Quick answer
Llywelyn is a boy name.
Pronunciation: Welsh /ɬə.ˈwɛl.ɨn/; Welsh /ɬə.ˈweːl.lɪn/; English /lu.ˈɛl.ɪn/.
Meaning and history
Probably a Welsh form of an unattested old Celtic name * Lugubelinos, a combination of the names of the gods Lugus and Belenus, or a compound of Lugus and a Celtic root meaning "strong". Alternatively it may be derived from Welsh llyw "leader". This was the name of several Welsh rulers, notably the 13th-century Llywelyn the Great who fought against the English.
Notes and context
Usage: welsh