This is the 13042nd most frequent Russian word.
максимальным
"Максимальным" means "maximal" or "maximum" in English.
The word 'максимального' is used adjectivally here to describe the noun 'уровня', indicating the highest level possible.
Мы достигли максимального уровня напряжения.
We have reached the maximum level of tension.
The word 'максимальную' is also an adjective here and modifies the noun 'отдачу', referring to the largest output or benefit achievable.
С этим устройством вы получите максимальную отдачу.
With this device, you will achieve maximum efficiency.
Here, 'максимальные' is the plural form of the adjective, describing 'усилия', emphasizing the greatest possible amount or degree of effort.