Shapes make up the majority of your layers in any given design. Figma has some basic shapes you can use as your building blocks. Rectangle Line Arrow Ellipse Polygon Star
You can apply different strokes and fills to any shape including the rectangle shape. You can change the colour by clicking on the swatch, and choosing the colour of both the stroke and the film you can also choose to apply a stroke to selected sides of your shape.
Radius You can choose to apply radius is to your rectangle shape you can either apply to one corner or you can apply to all corners. The properties box will allow you to selectively put in the value for your radius. Alternatively, you can use your mouse and hover over the shape and points will come up which will allow you to adjust the radius.
Lines Arrows
The line and arrow tool is very straightforward. You can select the colour using this watch in the properties panel and you can change the width of the stroke. You can change the direction of the arrow, all of the line by using the rotate tool.
You can also apply a drop shadow to the arrow line to the fact you can do this to all the other shapes just simply select the shape and then the properties panel go to drop shadow and you should be able to select a colour for your shadow and putting blur properties and spread properties, using numerical values.