In essence, it is a non binding vote of confidence or no confidence. This is a way for members of congress to comment on the proposed emergency action, or past use of executive orders. A US president can act without the approval of congress, the theory being that some situations arise so quickly that getting congressional approval would be too slow.
In this case, the claim of an actual emergency is somewhat dubious, as is the effectiveness of a physical wall. Going after the employers that pay the salaries of illegal immigrants... why they come here... would seem to be a more effective and less expensive solution, yet that isn't being proposed.
Congresspeople are using these resolutions to send a message to their constituents - this is how I feel on this particular subject... keeping in mind House terms are two years, so they're all up for re-election in one year. Congressional to executive communications aren't typically done in a public manner like this. These resolutions are more a public announcement of an impasse.
Consider another non binding resolution shot down by the House recently is HR1071. On the surface, it looks silly - recognizing that allowing non citizens to vote in the US devalues the votes of citizens. In reality, it's election year posturing, as opponents to current Dem representatives will certainly cite this vote in the 2020 house campaigns, even though the resolution has no real meaning.
This sort of exchange between legislative and executive branches as regards presidential authority is not without precedent. As recent as 2014-2106, when Obama faced a republican controlled senate, he resorted to executive orders that did not require congressional approval, specifically on issues such as DACA and the Paris Accords.
Both sides sort of have egg on their face on this one, because the very people who objected to Obama's use of executive orders as autocratic and against the will of the electorate, aren't protesting this. Nor are the people who approved of Obama's use of executive orders in defiance of congress, supporting this similar use of executive power. As an example of the awkward position all of congress has put itself in, consider this recent Hill article that points out the McConnell was right, in 2014.
Of course, that begs the question of why The Hill didn't write that article in 2014... but that's another debate entirely.
The danger here is that a future president's ability to react quickly to a changing situation by issuing an immediate order can be in trouble. Sadly, both parties have abused the concept of presidential authority.