The person icon is the icon of one of the node's labels.
A node may have multiple labels. Right-click on a node to open its context menu, then choose "Add Label" to add additional labels.
Each label may display an icon in addition to text. Press and hold CTRL and left-click (repeatedly) to select a label inside a node. Use "Icon Properties" in the properties view in yEd's lower right corner to choose an icon. You must stick with label property "Configuration" set to its default value "Standard", though. If the "Configuration" is changed to "Cropping", the label icon is no longer displayed.