LMMS has a lot of delays and reverbs, but the categories can be broken down so that they are easier to understand:
This is a very simple delay, called an echo. Delays like this do not incorporate reverb. They simply repeat whatever signal they receive. Adjust the delay knob to get a longer or shorter delay. Use the Dry/Wet Balance knob to adjust the level of the delay to the original signal. Play around with these settings and listen to the result.