Secrets are used sensitive information like user names and passwords. Creating a secret is fairly easy. We need to create a hash and store it into a secret:

apiVersion: bitnami.com/v1alpha1
kind: SealedSecret
metadata:
  name: pgpool-secret
  namespace: db-test
  annotations:
    sealedsecrets.bitnami.com/namespace-wide: "true"
spec:
  encryptedData:
    BACKEND_PASSWORD0: HASH_VALUE
  template:
    metadata:
      name: pgpool-secret
      namespace: db-test
      annotations:
        sealedsecrets.bitnami.com/namespace-wide: "true"

After that we can use this secret into a deployment for example:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: pgpool
  namespace: db-test
spec:
  replicas: 3
  selector:
    matchLabels:
      app: pgpool
  template:
    metadata:
      labels:
        app: pgpool
    spec:
      containers:
      - name: pgpool
        image: pgpool/pgpool
        envFrom:
          - secretRef:
              name: pgpool-secret           <- THIS
          - configMapRef:
              name: pgpool-volume
          - configMapRef:
              name: pgpool-config
        volumeMounts:
        - name: pgpool-volume
          mountPath: /config
        - name: secret-volume
          mountPath: /etc/secrets
          readOnly: true
      volumes:
      - name: pgpool-volume
        configMap:
          name: pgpool-volume
      - name: secret-volume
        secret:
          secretName: pgpool-secret

This will export this variable: BACKEND_PASSWORD0