Parish Councils have a wide range of powers at their disposal. However, they can only undertake activities for which they have a specific power. The Parish Council also has discretionary spending power (Local Government Act 1972 s137). A parish council may, subject to conditions, incur expenditure which in its opinion is in the interest of, and will bring direct benefit to, its area or any part of it or all or some of its inhabitants.
A list of powers can be found in the following link parish-council-powers-and-responsibilities
A description of the role of a Parish Councillor can be found here: Role of Parish Councillor