Jawahar Lal Nehru

In the word or name "Jahawarlal" or "Jawahar lal" as in "Jawaharlal Nehru", does the word "Lal" mean "son" or it means "ruby" which is red in color? Laal literally also means the color red.

The meaning may be getting confused because of similar words "laal", but in India "laal" is a common word for "son" and there are lots of literature full of such use, without any reference to "ruby" etc. 

In the name "Jawaharlal Nehru", the last name is believed to have come from the word "nahar" नहर which is Hindi word for canal, but another similar word "naahar" नाहर means "lion" / शेर. 

These websites which expertise in telling meaning of Hindi names, explain:

1) Name: Jawaharlal; Meaning: Triumph http://babynamesworld.parentsconnect.com/meaning_of_Jawaharlal.html

2) Jawaharlal's language of origin is Sanskrit and it is predominantly used in Indian. The name Jawaharlal means 'victory'. http://www.babynamespedia.com/meaning/Jawaharlal

Now coming to the word "laal" or "लाल": 

1) laal लाल Indian (northern states): Hindu name found in several communities, meaning ‘darling’, from Sanskrit lala ‘cajoling’ (related to Sanskrit lalana ‘caressing’). In several modern Indian languages lal is a term of endearment for a child; it is also an epithet of the god Krishna. http://www.ancestry.com/facts/lal-name-meaning.ashx

This explanation seems very credible because it tells how the word originated. Babies make a "la la" sound without even knowing a language, so the word "lal" would have come from that for small kids. Also note that the Sanskrit word lalana लालन or लालना meaning caressing (for babies) indicates towards the meaning too. 

This is why "lal" is used in compound names like Brajlal ब्रज लाल for Krishna where ब्रज / Braj is the place where Krishna lived during childhood and hence he was called as ब्रजलाल (Braj's son / Braj's kid). 

Brajlal is also a common name in India and one can google search to read many news with persons with this name. For example here is one:अफसरों की पीठ ठोंक गए ब्रजलाल 

Krishna was also called "lalla" मेरे लल्ला by his mother, as it appears in this poem:

पाँच साल का लल्ला मेरा
जा रहा है मधुवन में
गैया नही, बछड़े है साथ
बछड़े ही चरायेगा न बचपन में
...
ऐसे ही अटखेलियाँ करते
लल्ला लौट रहा है घर को
वही श्यामल-सी रंगत,मोहिनी सूरत
और सजी है वंशी उसके अधर को.

I also agree with a person who says: 

The often-found suffix "-laal" in north Indian names has nothing to do with rubies and red, I believe; it is added after the first name of a person just like some others add, for example, "-kumar--kumari", "-pati", "-ba/-bai", and "-singh" (note I'm not talking about the last name "Singh").
I believe that the suffix "-laal" to north Indian names comes from the word "lala", associated with a respectable merchant:
refer to http://dsal.uchicago.edu/cgi-bin/philologic/getobject.pl?c.7:1:2616.platts