Translation:It is necessary to emphasize several things.
Once more, "several" is not the same as "many". The Cambridge Dictionary defines several as: some; an amount that is not exact but is fewer than many. Thus the terms are not interchangeable. http://dictionary.cambridge.org/us/dictionary/british/several_1
I have frequently seen "plusieurs" translated as "many" but it seems to change the effect. Take the sentence above, for example: Il faut souligner plusieurs choses. Say you are trying to clarify some issues with someone with whom you are negotiating, and you say "I have several things to emphasize" (well, okay, there are a few points to consider), but if you say "I have many things to emphasize", then you might want to call for a bathroom break before you launch into a marathon session to go over all those points.
The translation "a number of" for "plusieurs" was not accepted here, oddly enough (I even noticed that they included the phrase as a possible translation for the word in the pull-down menu). Of course, it's one of those "in the eyes of the beholder" type of phrases, but so (in a way!) are "several" and "many."