The nations have become highly competitive and to some extent saturated with respect to their resources and production capacity. Hence, more and more nations tend to come closer to benefit from each other. With this intention, treaties are signed by nations (two or more), several nations join to form groups and alliances and international bodies etc. One such agreement is a reciprocal agreement that is signed by two nations to return the benefits they receive from each other. Philippines and Vietnam are into such a reciprocal agreement and therefore offer each other explicit visa benefits. 

A Philippines citizen does not need a visa if he plans to make a trip to Vietnam that has a duration of less than or equal to 21 days. You may enter Vietnam via any route, for any purpose without a visa if it is for 21 days. If you wish to make a trip that will last longer than this, then you will have to apply for a visa. Some people get into Vietnam utilizing this exemption and once there, try to extend the visa. This is a wrong practice as extending a visa there will be more time and money consuming. So be careful while planning your journey.

Does Philippines citizens need visa for entering Vietnam or not?

No, luckily, Philippines citizens do not need a visa for entering into Vietnam. Philippines citizen have been exempted from obtaining a visa for short duration stays going to a max of 21 days. So any Philippine can make a humble tourist trip or a short business visit without actually going through the hassle of obtaining a visa. In addition to this, if your spouse or parent is a Vietnamese citizen or you are a foreign-based Vietnamese citizen then you can avail an exemption for a longer duration (up to 5 years max) provided you complete the documentation. There are a few other exemptions as well and you can get all the information that you need from the embassy. However, that does not mean you will not need a passport. The traveler needs to have a valid passport in spite of the visa exemption.