When used as a noun, the word training is an uncountable noun or a material noun, so there is no plural form. The word training can also be used as a verb or adjective.

He needs more training. (material noun)

He is training for the Olympic Games. (Present participle of verb string)

He took part in two training sessions. (adjective)

.....................

You need to attend some important training next month.

Next month, you need to receive three important trainings.

Next month, you need to receive training in three important areas.

4. Tomorrow, please train new employees.

Next week, I will go to your school to listen to teacher Zhang, who teaches very well.