Complex sentence: Neris (,,) is a river rising in Belarus, flowing through Vilnius (Lithuania) and becoming a tributary of the Neman River (Nemunas) at Kaunas (Lithuania).
Split into simpler sentences: Neris (,,) is a river rising in Belarus. It flows through Vilnius (Lithuania) and becomes a tributary of the Neman River (Nemunas) at Kaunas (Lithuania).