Hi @AbhishekHP,
looking only at the coefficients is a bit risky. Your first regression has an R^2 of practically zero so you should not interpret anything really. The problem is that your x variable (work_days) has very little variation. Theoretically the smaller the variation in the dependent variable, the larger the error of the OLS estimator. Intuitively, if your x is almost constant it can barely have a chance to "explain" any variation in a given y.
Further, in both regressions the p-values of both coefficients are above 0.1 (which relates again to the issue of too little variation in your x variable). So, I wouldn't conclude anything based on these regressions apart from that there is insufficient evidence (data) to show any relation between work_days and sale.