The Second will aim to put his/her bowls close to the jack of the lead has not done so. Otherwise, he/she will follow the Skip's advice and provide positional bowls and/or draw to an imaginary jack.
The Second should leave the head in good shape with bowls around the jack, back bowls and position bowls.
Occasionally a Second may even be asked to break up a head with a drive. The objective is to give the Skip every chance to complete the end successfully.
When the Skip is on the mat, the Second should only offer advice to the Skip when asked or when the head has altered. Too often a Second fails to advise the Skip when there is a change in the head i.e. from being one up to one down. The Skip must be made aware of any changes as this will influence his/her choice of shot.
A Second must be good at reading the head and giving advice if necessary.
Finally, a Second must be a good communicator and give clear signals at all times. Now you can see that a good Second is the heart of the team.
More information here.