They can manipulate objects around them and have a whole array of tools and weaponry based around this fact (mainly gauss-like weaponry).  They can also focus pressure into certain areas (as so to flip a switch and whatnot).  Some of the more advanced ones can levitate themselves, but generally they make use of constructs that they can better control with their minds.  This telekinetic ability is what they have for the most part, other psionic capabilities are rare.

A crewed spaceship of them can use their abilities to manipulate the movement of their spaceship (in a way that is akin to a reactionless drive) and redirect missiles along with slow down projectile attacks.  They also can steer their own projectiles into enemy ships.  Mind you, that this is unable to deal with laser/beam attacks.  Also overwhelming them with projectiles works as they won't be able to catch them all.

Weapon wise they tend to use kinetic weaponry augmented with their psionic capabilities.  They never invented lasers due to their different tech path.  What computer systems they developed natively are stuck in the 1950's and pretty much are just used for keeping track of information.

All of this is limited by the drawbacks I mentioned earlier as despite each member of their species having telekinetic potential, it is not something they know intuitively and must learn.  Feats such as described able can take decades to truly hone in and their growth/reproduction is very slow to begin with, which is why major losses to their population aren't easily repaired.