1——what does mean 便让 and 系(jì)?
便让新王后帮助他系在脖子上。
便 is a conjunction, you can translate it into "and" or "so", it depends on the context.
让 means "ask somebody to do something"
系 means "tie something"
2——what does mean 勒 and 昏死and 过去?
于是新王后用彩带把公主勒得昏死过去。
勒 strap
昏死 means faint or comma
when 过去 is placed after verb, it means it is past tense.
Translation of the sentence: So/then the new queen strapped the prince with a colorful ribbon and caused her coma.
3——what does mean 救醒?
但小矮人们回来后救醒了白雪公主。
救醒 means "to save someone and make him/her alive again"