I am not sure what you are asking. Are you referring to the opening in the floor? Are there stairs going down from there? Did you intend to post additional pictures?

Hi, the empty space where the railing makes an L-shape. Yes those are the stairs

Is that headroom for steps going down?

Leave all the railing in place for safety reasons.

I'd buy or build a cabinet or bookcase or table or "desk" that fits between the back of the loveseat and the railing (face it toward the photographer.)

Alternately, a large square wood footlocker might fit there.

https://www.dormco.com/Bolt_Trunks_Pacific_Teal_Dorm_Trunk_with_Wheels_p/bolt-xw14a035pateal.htm

Like plants in the room, so einportlandor's idea would be worth considering IF the area gets enough sunlight for a plant to remain healthy, you might consider one but you'd not want to set it on a table -- you'd need to be sure it would not get knocked off into that space behind the rail.

That's true. I did like the bookcase or cabinet as well. I am nervous to put a table with anything decorative on top because it may get knocked off and fall below.

You might consider wrapping the area in glass panels intended for the railing of a deck, balcony or stairs. Wood would block light you might need for the steps.

If you created a wood top rail (and added a wood support on the wall without a rail), you might be able to set a Lucite panel or thick safety glass panel (or one way mirror - mirror side up) atop it. You could have the clear panel framed as if it were a picture and affix its wood frame to the wood railing.

Yes, a big plant in a sturdy heavy pot on the floor. No danger of it falling overboard.

Was wondering if the light is coming from a skylight? Reason i ask and do you mind live indoor plants because an english ivy would love that railing using a few low and long narrow planters....

***Guardrail spindles do NOT look like they meet IRC building code.

That is a great idea! Love it. Thanks

I would make that pony walls so furniture could sit in front without seeing the back at all.

Not a Pro.

I am with the above Poster.

A grouping of plants would be ideal.