what does this language mean?

[MR.]

while (!IsTradeAllowed()) Sleep(500);

[Fernando Carreiro]

Please learn to read the documentation — MQL4 Reference

while loop operator

Performs an operator until the expression checked becomes false. The expression is checked before each iteration

IsTradeAllowed

Checks if the Expert Advisor is allowed to trade and trading context is not busy

Checkup

Sleep

Suspends execution of the current Expert Advisor or script within a specified interval

Common Functions

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