I'll confine myself to community pharmacists as the situation is slightly different in a hospital setting.
Pharmacists are free to give healthcare advice on all medical issues. They have to have a quiet area or room where a patient can speak to them in privacy over issues that some might find embarrassing such as piles. They are free to provide advice on simple medical problems such as the treatment of colds, sore throats etc. They are obliged to direct the patient to the GP in circumstances where a patient might have complex or multiple medical issues. They are intended to be one of the first advice providers over things like smoking cessation, weight-loss, healthy eating, the morning-after pill and pregnancy testing. They have a role in monitoring the INR of patients who are on warfarin to ensure that the dosage is correct and have a duty to recommend changes to the patient and alert the GP. They have a role in reviewing your medicines and will ask how long you've been on a medicine, how you take them and can advise changes. They are sometimes more familiar with interactions between medicines and should alert you to any problems in these circumstances. They are obliged to state how a medicine should be taken eg not at the same time as milk, on an empty stomach etc and can provide advice on the storage of medicines
In all circumstances, the pharmacist has to be constantly aware of the limitations of his/her knowledge and must direct the patient to the GP where there is any doubt. Theoretically, one of their main functions is reduce the workload of the GP but it doesn't always work for very many reasons.