das Pflaster
adhesive bandage
A small, self-adhesive bandage that is stuck onto a small wound or injury to protect it.
Nach dem Sturz hat sie sich ein Pflaster auf das Knie geklebt.
After the fall, she put an adhesive bandage on her knee.

bandage / pavement / patch
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adhesive bandage
A small, self-adhesive bandage that is stuck onto a small wound or injury to protect it.
Nach dem Sturz hat sie sich ein Pflaster auf das Knie geklebt.
After the fall, she put an adhesive bandage on her knee.

'Das Pflaster' for a wound is not the same as the English 'plaster' for walls. The material for walls is called 'der Gips' (plaster) or 'der Putz' (render/plaster) in German.
Ich habe mich geschnitten, hast du ein Pflaster für mich?
I cut myself; do you have an adhesive bandage for me?
You can easily recognize the meaning from context. If someone is talking about a 'Wunde' (wound) or 'Verletzung' (injury), it means the small bandage. If it is about a 'Straße' (street), a 'Gasse' (alley), or the 'Altstadt' (old town), it means the stone surface.
Die kleine Wunde am Finger blutet, kleb bitte ein Pflaster darauf.
The small wound on my finger is bleeding; please put an adhesive bandage on it.
When you stick a 'Pflaster' (adhesive bandage) onto a wound, you use the preposition 'auf' with the accusative. When the bandage is already on the skin, you use 'auf' with the dative.
Die Mutter klebt ihrem Kind ein Pflaster auf das Knie.
The mother puts an adhesive bandage on her child's knee.
The expression 'ein teures/hartes/gutes Pflaster sein' describes the living conditions in a place. It is often used to talk about the costs or difficulties in a city.
Berlin ist für Künstler kein einfaches Pflaster mehr.
Berlin is no longer an easy place for artists.
When a 'Pflaster' (patch) releases an active substance, it is often described more precisely, e.g. as a 'Schmerzpflaster' (pain patch) or 'Nikotinpflaster' (nicotine patch). The context here is always medical and refers to longer-term treatment.
Um mit dem Rauchen aufzuhören, benutzt er ein Nikotinpflaster.
To stop smoking, he uses a nicotine patch.
surroundings / environment
'die Umgebung' and 'das Pflaster' can both mean a place or environment in which someone moves around. 'die Umgebung' is neutral and general: it can be the area around a place or a person's social environment. 'das Pflaster' is used more figuratively in this meaning and often with an evaluation, for example 'ein teures Pflaster' (an expensive place) or 'ein hartes Pflaster' (a tough place). For a normal description of an area, 'Umgebung' fits better. 'Pflaster' sounds more natural when you want to say what a place is like for living, working, or shopping.

Die Innenstadt ist für kleine Geschäfte ein teures Pflaster.
The city center is an expensive place for small shops.
Die Umgebung des Hotels ist ruhig und grün.
The surroundings of the hotel are quiet and green.