herb phoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhonetic PhoneticPhoneticPhoneticPhoneticPhoneticphonetic noun [C] 
a type of plant whose leaves are used in cooking to give flavour to particular dishes, or which are used in making medicine 
Basil, oregano, thyme and rosemary are all herbs.
A large range of herbs and spices are used in Indian cookery.
Do you prefer dried or fresh herbs to cook with?

herbal phoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhonetic PhoneticPhoneticPhoneticPhoneticPhoneticPhoneticphonetic adjective [not gradable] 
Herbal means relating to herbs or made from herbs. 
She believes in the beneficial properties of herbal remedies.
Have you ever smoked herbal cigarettes?

Herbal tea is another word for tisane. 

herbalist phoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhonetic PhoneticPhoneticPhoneticPhoneticPhoneticPhoneticphonetic noun [C] 
A herbalist is a person who grows or sells herbs for medicinal uses. 

herby phoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhoneticPhonetic PhoneticPhoneticPhoneticPhoneticPhoneticPhoneticphonetic adjective INFORMAL 
This salad dressing is nice and herby (=It tastes of herbs).
( Cambridge International Dictionary of English )