You can define the block label and then include it in a master block or block view. If you include the label in the master block, then the value assigned to the label is the same in each block occurrence. If you include the label in multiple block views, you can assign a unique attribute value to each occurrence.
Choose Sketching tab→Blocks Group→Block Label: 
. The Block Label Properties dialog box is displayed for you to define the behavior and properties of the label.
In the Name field of the Block Label Properties dialog box, type a label name. For example, if the label is for a particular switch or resistor, you can use the Name field to designate its part number.
In the Value field, type a value for the label. For example, if there are multiple instances of a particular switch or resistor, you can use the value field to assign sequential numbers to each occurrence.
To create a label that contains variable property text that is updated automatically, first click the Property Text button 
, and then select the property text source and property text attribute. To learn more about selecting property text, see these Help topics, Using Blocks and Using Property Text.
Description--Type a description or prompt for the block label name-value pair.
Set or clear these options as desired:
Show in Block Occurrences--When set, the label name is displayed when you place a block occurrence. When cleared, the label name is not displayed.
Use Same Value in All Occurrences--When set, the same label value is used for all occurrences of the block. If you edit one occurrence value, you change the value in all other instances of the block. When cleared, you can assign a unique value to the label when a block occurrence is placed. This option is cleared by default.
Ask for Value During Placement--When set, the Block Label dialog box is displayed as a prompt to confirm the default value or enter a new value for the label.
Lock Position within Block--When set, the location of the label in all occurrences will be the same as the master block or block view.
Edit the label text options as desired. The default settings for style, font type, font size, color, text justification, and angle are derived from the dimension style currently selected on the Block Label command bar.
When you click OK, you are prompted to click to define the origin point of the block label. Move the mouse cursor to the location you want to place the label with respect to the block graphics. As you move the mouse, you can use any of the displayed graphics keypoints to help you position the label, but the label will not connect to the keypoint when placed.
Alternatively, you can type the label placement coordinates in the X and Y text boxes on the command bar. Press ENTER to apply the coordinates.
Click to place the label.