.blocHeader {
  background-image: url(./images/team-taking-meeting-notes.jpg);
  box-sizing: border-box;
  height: 350px;
  width: 100%;
  background-size: cover;
  background-position: center center;
  background-repeat: no-repeat;
  display: flex;
  justify-content: center;
  align-items: center;
}

<div className="blocHeader">
  <div className="blocHeader-content">
    <div className="blocHeader-title">
      {!loading && (
        <h1 className="text-center text-light display-2">
          <Translate tid="Accueil_title" /> {prenom}
        </h1>
      )}
      <p className="display-4 text-center text-light">
        <Translate tid="Accueil_subTitle" />
      </p>
    </div>
  </div>
</div>