How I can interpret the attached tree?
Initially in the uppermost node, you have 30 samples or data points that needs to be classified into yes/no category. Out of 30, nearly 27 are with no label and 3 are with yes label. 

In the next level, it gets divided on the basis of poutcome value. Records in left side of the tree at level 2 are one with poutcome value is non-existent or fail while that on right hand side are with value success.