It depends what you mean by merging actions in the *NLA Editor*. You can merge 2 strips to make one in the *NLA* but if you just want your character to have a coherent animation, i.e. have the same position at the beginning of the second action than the one at the end of the first action you can do it this way:

- Open the *Graph Editor*. In the *NLA*, select the second strip. Press <kbd>tab</kbd> so that you can see all the bones curves in the *NLA*.
- As the master bone of your armature is *Hips*, and as the shift between the 2 actions position is on its *Z* location, select the *Hips Z Location* track and press <kbd>shift</kbd><kbd>H</kbd> to make all the other ones invisible.
- Select the curve with <kbd>A</kbd> and move it on its own Y axis, you can see that the armature moves in the 3D view. Move it where it is supposed to be.
- Correct on any other axis if needed.


Now keep in mind that it doesn't seem to have any transition between the 2 animations, maybe it's better to create one. Also, instead of keeping two separate actions, you can choose to select all the animations of the second action in the *Dopesheet* and paste them at the end of the first one. You'll have to correct the position the same way as explained.

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/ZvWeD.jpg