How to change the STR of the data

Hello everyone!

I am doing a moderation analysis using R. However I encountered a problem in performing the said codes because one of my variables is character. Do you perhaps know how to restructure the variable itself?

My topic for this test is: Do net changes in cash and cash equivalents moderate the relationship between liquidity and profitability? - Moderation

This is the code I used:

fit1 = lm(PROFITS ($M)~ Net change in cash and cash equivalents +Net liquidity+ Net change in cash and cash equivalents*Net liquidity,data=LBYACST_Dataset)

I am also pasting the screenshot of my work.

Thank you so much!!