Lysimachia ciliata 'Firecracker' perhaps.

Thank you so much. I'll look it up and learn how to take care of it.

Hi, do you still think this is a Lysimachia ciliata?

Yes, the id stands. But be aware that this is the cultivar Firecracker or similar. If you just look up L ciliata you will find green leaved plants. It doesn't need any 'taking care of'. Just keep an eye on it as it has a tendency to roam.

Are all these plants in that one small bed you showed in another post? The only thing which I would recommend as regards care is defining the edges of the bed more clearly to deter the lawn from creeping into the bed. While the rocks might look pretty they are difficult to keep clear of weeds. A sharply edged bed (do it with a spade or edging iron) looks smart and keeps grass at bay. Also a mulch of compost or something else would protect the soil (it looks rather battered down in the pictures). Otherwise none of the plants you have shown so far needs any particular care other than keeping tidy.