The adjective सारा means “all”.
सारे लोगों ने उसे नदी के पास भागते हुए देखा – “Everyone (i.e. all of the people) saw him running near the river”
काश कि सारे लोग आप के जितने दयालु होते – “I wish that everyone were as kind as you”
इस देश में सारी जगह ऐसी नहीं होती – “Not every place in this country is like this”
It is used in several idioms.
“खूब सारा” means “lots”, “a lot of”, “plenty of”, etc.
मैंने खूब सारी रोटी खायी – “I ate quite a lot of bread”
The expression “ढेर सारा” means something like “loads of”, “tons of”, etc. “ढेर” literally means “pile”, “load”, etc.
मैंने अपने बालों पर ढेर सारा तेल लगाया – “I applied loads of oil on my hair”
The expression “इतना सारा” means “so much/many” (in an emphatic way).
तुम इतने सारे पकोड़े क्यों खा रहे हो? – “Why are you eating so many pakoras?”
The expression “बहुत सारा” means “very many”.
बहुत सारे लोग भाषण सुनने आये थे – “Many people came to hear the speech”