The phrase appears in both Irish Gaelic and Scottish Gaelic.

In both, it means "A Hundred Thousand Welcomes".

In Irish Gaelic, it's spelled Céad Míle Fáilte. In Gaelic (Scottish), Ceud Mìle Fàilte.

That's fine for a sign in a pub or shop. But to be grammatically correct, if you're saying it to a person, it should be "A hundred thousand welcomes to you" :

Céad míle fáilte romhat (Irish Gaelic) or Ceud mìle fàilte dhut (Scots Gaelic).

It's pronounced kayd meela foll-tja rót in Irish Gaelic,

and kee-ud meel-a faahl-tja ghooht in Scots Gaelic.