String Values in a data frame in Pandas
To convert from string to float in pandas (assuming you want to convert Employees and you loaded the data frame with df), you can use:
df['Employees'].apply(lambda x:float(x))

You have not given enough information about your input and expected output. So let us assume that hospital name or anything for that matter which is the input for your model is nan. You would like to remove it from the dataset because extracting features from 'nan' wouldn't make sense. Apart from that, if they are just other peripheral features, then it might be alright. In that case, if you wish to convert them into blank, then use:
df.replace(np.nan,' ', regex=True)`

Else, if you wish to remove that frame, you can check for nan using this.