In design, different shapes have different meanings. Above, there are 6 different shapes, and when used in design, they can express different connotations and feelings.
The circle is a soft, harmless shape that is welcoming. In certain contexts, it can be seen as feminine shape.
The vertical rectangle is an ‘authoritative’. The lack of curves (unlike the circle) give it a more serious nature.
An arrow is a bit more of an obscure shape (compared to the obvious circle, square etc.), but it shows direction. In design, it can be used to leads someones eye
An upright triangle is a strong shape. As a visual and in reality. This can show stability and reliability.
Although it is still a triangle, an upside down triangle can have the opposite meaning upright one, as it is in an unstable position.
This shape can be seen as a ‘dangerous’ shape. The sharp edges and irregular angles can represent sharp teeth, spikes, broken glass etc.
Designers and companies use this method and their products/packaging are certain shapes to appeal to the target audience. Such as a beauty product like lipstick will appeal to women more than men so they may be more curvy, resembling a womans body, and a male beauty product such as shaving foam will be more square and less curvy to add masculinity.
While I was at work, I was stacking shelves and noticed this method on the health & beauty section. (These aren’t my pictures but you can see what I mean).
As you can see, the female product has curves and is more slender than the Old Spice bottle, which is stocky and more rectangular.
I looked at male and female fashion brands and again, most of followed this method (the only ones that didn’t were mostly brands that made clothes for both genders). The Gucci logo used a slender font and the icon is a mainly rounded shape. On the other hand, the Diesel logo is bold and in uppercase, also it’s very rectangular and in a bold, blunt font.