Echo and reverb are usually a different sound fx.
Echo fx (can also be called delay fx) "bounces" from surfaces (for example walls of the room) in a easily noticeable time intervals, that might sound similar to a rhythm of a "ping pong" ball when hitting the table back and forth.
Reverb fx is also based on sound bouncing, but in much larger number of bounces that causing them to build up first and then fade out while absorbed with the surrounding space the sound was emitted in.
Right now Godot is able to add a reverb. Echo might be possible in the near future, after audio engine rewrite.
In Godot the basic node that is in charge of playing samples is SamplePlayer node.
In the SamplePlayer's node Inspector tab you will see the parameters called
Reverb Room and
Reverb Room sets the space preset - simulating spaces from small room to huge concert Hall. Just make a choice of the size of the space you wish the sound to reverberate. Reverb in small room is short and lets you "hear" the room and it's walls that are close to the listener. Reverb in a huge Hall is long and vast creating impression of big, empty space.
Reverb Send regulates how much reverb you add to the original sample (original reverbless sound is usually called "dry" as contrasted with "wet" sound when reverb is being added to the sound ).
Value from 0 (no reverb added, so the sound is "dry") to 1 (full reverb added, so the sound is going to be very "wet").