Funeral or "GNAN SOP" means ceremony for deceased persons. A feast is organized to honor the deceased person. The ceremony date is scheduled by monks.
Funerals in Thailand are regarded as important events because they represent rebirth and the passage from one existence to another. The older and more respected an individual is the more elaborate the funeral rites. Most Thais are cremated in accordance with a Buddhist ritual. The formal wake period is seven days. At that time the body is taken to a house of a morgue where it may be kept for days or even years until it is cremated.
Funerals for Thai Buddhists can go on for much longer than what you may have seen before in the West. It could last from anything from one week to a year or two. Depending on how close you were to the deceased, you probably won’t be expected to attend every part of the funeral. For the parents of colleagues at work I probably would only attend the cremation on the last day. For relations of friends you probably would attend at least one if not all of the chanting sessions. If you are close to the family then it might be appropriate for you to bring a wreath. Either that or give the family some money in an envelope.