This is a piece of advice which means that one should not concentrate all efforts and resources in one area as one could lose everything.
Example:
Mr Tan’s financial adviser urged him to be careful and not put all his eggs in one basket by investing all his money on stocks.
'Eggs' are delicate, and if all of your eggs were in one container, and that container was damaged, you might lose all of your eggs in one quick and painful moment.
1) You don't want to keep all of your eggs in one basket. You might lose everything!
2) Tom had all of his eggs in one basket -- Yoyodyne.com stock -- and when the stock market crashed he was bankrupt.
proverb Don’t risk everything on the success of one venture:
we need to be more tactical and not put all our eggs in one political basket