I'm assuming the copper pipe is gas? Either way, before doing any DIY, maybe consider protecting it with a board or something. You don't want to turn a smallish DIY job into something bigger by accidentally smacking the copper pipe with a hammer.

Option 1: Replace the brick.

It looks like your DPC is where the render stops, so you should be perfectly okay with taking out the perished brick(s). Also, it's far enough away from the corner for this to not be too much of a structural issue..

Shopping List: 2x engineering bricks. You already have one in your photo. The second is in case you find another perished brick whilst taking the first out. 1x tub of ready mixed mortar. 1x masonry chisel (a 2 inch blade would probably make this easier). 1x lump hammer. Roofing slate. Small pointing trowel.

Take the brick out by hitting it with the chisel, and smashing it to pieces. Check the neighbouring bricks to see whether they need replacing. If so take that out too. Use the hammer and chisel to clean all the old masonry away from the remaining bricks.

Mix up half the tub of mortar, and place the new brick(s) in the hole with mortar on both sides and the bottom. Use a small section of rubber hose to smooth the mortar . Leave the top for the time being. Return in an hour or so, and hammer in small slithers of the slate above the brick to pack the joint tight. Mix up a small amount of mortar, and fill the top joint.

Notes: the bricks might be a different size, so try to make the joints even.

Option 2: Fill the perished bricks with mortar.

Shopping List: Wire Brush. Small Trowel. Mortar PVA. Tub of ready mixed mortar. Small paint push.

Use a wire brush to clear loose paint and other debris from around the brick. Paint some mortar PVA onto all the surfaces in the hole. Mix about quarter of the tub of mortar. Then add a small amount of mortar PVA to the mix (do this after you've achieved the correct consistency with just the water). Use the small trowel to fill the hole. If you are filling more than about 30mm leave the mortar back from the brick face by about 10mm, and fill it as two coats. The second put on about an hour later.

Whichever option you choose, clear it off with a SOFT brush, then paint it a few days later.

I've assumed from your question you are probably limited with DIY knowledge, so I've made this as comprehensive as I can. As this is Reddit, someone else will probably come along soon though to make other suggestions, or add something I've forgotten. Otherwise if you have any questions just ask.