After Editing The Question:
mask_name = df['Name'].str.contains(r'.*(?:Ehsan).*')
mask_err = df['Error Name'].str.contains(r'(?:\bLine Error\b|\bDevice\b)')
df = df[mask_name & mask_err]
df.groupby(['Name', 'Error Name'])['Count'].sum().reset_index()
Before Editing The Question:
mask_name = df['Name'].str.contains(r'.*(?:Ehsan).*')
mask_err = df['Error Name'].str.contains(r'(?:\bLine Error\b|\bDevice\b)')
df.loc[mask_name & mask_err, 'Count'].sum()