OED has the following for committee:
3.a. A body of (two or more) persons appointed or elected (by a society, corporation, public meeting, etc.) for some special business or function. (Cf. 1b, which shows that each member was originally called a committee.)
Hence, in the usage of Parliament, or other legislative assemblies:
Committee of the whole House: the whole of the members sitting as a committee to consider the details of a measure which has been ‘committed’, or for kindred purposes, as in the Committee of Supply, Committee of Ways and Means; hence the phrases to resolve itself into a committee, to go into committee, to be in committee, etc. select or special committee: one consisting of a small number of members, selected to investigate a special matter. standing committee: a permanent committee appointed to deal with all matters within a particular sphere, during the existence of the body appointing them. joint committee: one composed of members nominated by two or more distinct bodies, such as the Houses of Lords and Commons, in order to arrange the terms of joint action, adjust differences, etc.
In terms of the UK Parliament, a select committee consists of around a dozen members selected for that particular committee, which usually has a particular remit (for example, the Public Accounts Select Committee, which deals with expenditure on public projects). The Parliament website has a detailed description of what they do.
We can't help with translation, though. Perhaps having read about the committees, you can identify an equivalent or analogous function within the French legislature whose name you could use. Perhaps it will be acceptable to use the English term, perhaps set in italics as a foreign expression. Perhaps you could simply call it a "special committee" and translate that.