The meaning of EMA

If I set up a 50 EMA on a one minute chart on MT4 on any currency pair, does that mean the 50 EMA line represents the average of 50 prices in the last 50 minutes or 50 days etc.? Does the chart timeframe (M1, M5, M15, M30 etc) determine if the 50 EMA line represents the average of 50 prices in the last 50 minutes, 250 minutes (M5 x 50), 750 minutes (M15 x 50) etc.? If so, how do we know that for sure is the case? Thank you.

50 means 50 bars on THAT time frame.