Pronunciation: Twah(low) - leh(high)
Its a West African slang mostly used by Nigerians. When said, its used to show respect, appreciation or salute someone with higher reputation or swag than you, or even jokingly with friends and family, most especially when you want something from them. For example: help or mostly money. Its said before and after the request has been granted.
In other words its used for praising a person in other to get something.
* These videos are coming directly from Youtube, they may or may not be most relevant to the word "Twale"