"I'm going out to have a meal."
Source: This is a common phrase used in Engpsh to indicate that one is leaving to go eat.
Examples:
"I'm starving, let's go out to have a meal."
(我饿死了，咱们出去吃饭吧。)
"I have a lunch appointment, I'm going out to have a meal."
(我有午餐约会，我要出去吃饭了。)