What do you mean by a Wattage of an incandescent bulb?
Watt (\$W\$) is the unit of Power (\$P\$). There is an equation that says:

$$E = P \cdot t$$

You can see that Energy (\$E\$) equals Power (\$P\$) times time (\$t\$). There is a linear relationship between Energy and Power, so the higher the Power (wattage) of a device, the more energy it consumes. 

The same formula, in a different form:

$$E=P \cdot t \rightarrow P=\frac{E}{t} \rightarrow W=\frac{J}{s}$$

One Watt means one Joule (\$J\$) per second (\$s\$) is being consumed. 60W means 60J/s is being consumed by the bulb.