trine is when its in the same element, but not the same sign. so libra and gemini are trine to aquarius. conjunct is when it's the same sign. like if you have both venus and mars in aries, then your venus and mars are cunjuct. opposition is when a planet is in an opposite sign from another planets sign. like if you're an aquarius sun and a leo moon, then your sun and moon are in opposition. a sextile is when two planets are in complimentary, but not the same element; for instance venus in aries and mars in gemini would be a sextile.
but sometimes it can be in uncomplimentary signs, if the degrees are just right. for instance, even though aquarius is the opposite sign of leo, someone with a pisces sun and a leo moon, could have their sun in opposition to their moon, if it is in the right degrees, for instance they are in the beginning of pisces.
The Conjunction - The conjunction is formed when two planets are at approximately the same degree of the same sign or at an orb of not more than 8 degrees. In a conjunction, the energies of the two planets are combined, and the result is often a strengthening of both.
The Sextile - Sextiles occur when two planets are approximately 60 degrees apart. This is the aspect of opportunity. It is the 3rd and the 11th house Hindu aspect. Initiatives can be taken during this aspect and it reinforces the weak points in life.It is a very benign aspect indicative of talent, confidence and popularity.
The Trine - A trine occurs when two planets are approximately 120 degrees apart. It is the 5th and the 9th house Hindu aspect. Trines bring about ease and comfort.This is a fortunate aspect for harmony, peace and does much to improve adverse aspects.
The Opposition - The opposition occurs when two planets are about 180 degrees apart.It is the 7th house Hindu aspect. As the name implies, opposition are obstacles that must be resolved.This is a malefic aspect of perfect balance. It includes confrontation and partnership. It indicates change of circumstances. Oppositions can manifest as mood swings.