Welcome
Welcoming
noun, verbal noun, の adjective
It's my delight to welcome you, so I give you a big, warm welcome.
歓迎 is a relatively formal word that refers to warmly accepting someone in, like welcoming someone who's arrived somewhere or joined a group.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
カウンターの上に「チップ大歓迎」と書かれた箱がありましたよ。
I saw a box on the counter that had "tips welcome" written on it.