A cerâmica exige paciência.

Portuguese often uses the singular noun cerâmica to talk about the craft, field, or material in a general sense.

So a cerâmica can mean:

• ceramics as a field
• pottery / ceramic work as an activity
• ceramic material in a general sense

That is normal in Portuguese, even if English often prefers the plural ceramics for the field.

A is the definite article and here it means the.

Portuguese very often uses the definite article when talking about a whole activity, art form, or category in a general way. So a cerâmica is a natural way to say ceramics / pottery as a discipline or craft.

English often drops the article in this kind of sentence, but Portuguese often keeps it.

Yes, cerâmica is a feminine singular noun.

You can tell here because it uses the article a, not o:

• a cerâmica
• not o cerâmica

If you add an adjective, it also agrees in the feminine:

• a cerâmica tradicional
• a cerâmica portuguesa

Yes. Cerâmica is a flexible noun.

Depending on context, it can refer to:

• the craft / art of making pottery or ceramic objects
• ceramic material
• ceramic objects / ware

In A cerâmica exige paciência, it most naturally refers to the craft or practice of ceramics/pottery, because that is what can require patience.

Exige is the 3rd person singular present indicative of the verb exigir.

Here is the basic pattern:

• eu exijo
• tu exiges
• ele/ela exige
• nós exigimos
• vocês / eles exigem

It is exige because the subject is a cerâmica, which is singular.

Because paciência is being used as an abstract noun in a general sense.

Portuguese often leaves out the article with abstract nouns when speaking generally:

• exige paciência
• precisa de tempo
• mostra coragem

So paciência here means patience in general, not some specific patience already identified.

If you wanted to make it specific, an article could appear:

• exige a paciência de um mestre
• exige a paciência que nem todos têm

They help show stress and vowel quality.

• cerâmica → the stressed syllable is râ
  Syllables: ce-râ-mi-ca

• paciência → the stressed syllable is ciên
  Syllables: pa-ciên-cia

For a learner, the most useful thing is to notice where the stress falls:

• ce-RÂ-mi-ca
• pa-CIÊN-cia

That matters a lot for sounding natural.

A simple stress guide is:

• a ce-RÂ-mi-ca e-XI-ge pa-CIÊN-cia

A few European Portuguese notes:

• the a at the start is very weak
• the first e in exige often sounds closer to a very short i
• unstressed vowels are often reduced

So in connected European Portuguese speech, it may sound more compressed than the spelling suggests.

A rough learner-friendly approximation is:

• uh suh-RA-mi-kuh ig-ZEE-zhuh puh-SYEN-suh

That is only approximate, but it gives the general rhythm.

You might see that in a title, headline, label, or note style, but in a normal full sentence, A cerâmica exige paciência is more natural.

So:

• A cerâmica exige paciência → normal sentence
• Cerâmica exige paciência → more like a heading or compressed style

Yes. Requer is possible:

• A cerâmica requer paciência.

That sounds a bit more formal or bookish.
Exige is very natural and common, and can feel slightly stronger, like:

• requires
• demands
• calls for

So exige is an excellent choice here.