#To select rows whose column value equals a scalar, some_value, use ==:
df.loc[df['A'] == 'foo']

#To select rows whose column value is in an iterable, some_values, use isin:
df.loc[df['B'].isin(['one','three'])]

#Combine multiple conditions with &:
df.loc[(df['column_name'] >= A) & (df['column_name'] <= B)]